I think as long as it's in some kind of box you should be ok sending it back! Sugar is absolutely going to love the Plaza and the Trixie wheel
It also comes with a shelf (if yours comes with the shelf) and you have the wood house (just check that over and make sure there are no nails sticking out anywhere!). Hopefully she won't chew the house, but keep an eye on that because they are made with nails! You can get some that aren't made with nails but I wouldn't worry about that just now - plenty of people have those rough bark houses without any issues.
So with the shelf and house and wheel and maybe a cardboard floor tunnel and one of those balls you would maybe only need to add a couple more hides. We could suggest a few things but it all starts to cost! Hence cardboard hides or pringles tubes (wiped out) are fine. With Pringles tubes though, I pull the silver foil out of the middle. It's quite easy. Once you've cut the metal end off you'll be able to get hold of one corner of the foil and then just gently pull and it all unravels and comes out in one piece
Basically for Syrians you need rat sized things! eg tunnels at least 7cm in diameter. Anything sold for hamsters is usually only big enough for little dwarf hamsters. But there are some good places to get things.
One of my favourite places is a site called Hamsters We Love. I'll link it below. They only sell hamster safe things
Be careful though it can be tempting ha ha.
One thing it would be good to buy though is some sprays. These are basically grain stalks - like millet, flax etc. You just stick them in the substrate and they look like little trees. They have a few functions. One is to ensure the hamster doesn't feel too exposed - they are prey animals so can often feel a bit nervous about being out in the open (especially when they're babies) unless there is plenty of cover. Things to dive under or behind. Then they start to feel more secure and are out and about more. The other thing is they add some enrichment and it's something for them to nibble and have some normal foraging behaviours. Something to do!
I do get mine from Hamsters we love. The only thing with anything like sprays (and hamster food and any treats that aren't human grade) is it's a really good idea to put them in the freezer for a week before using. This kills off any mite or bug eggs that could hatch out!
Particularly with hamster food. Unfortunately virtually all hamster food (and other pet food) contains moth eggs. Don't panic it is rare that anything hatches out. Only if it gets very warm sometimes. But freezing it for a week kills any moth eggs (I speak from experience there ha ha).
If just getting a few sprays then red sorghum, millet and flax would be a good start
One thing you might want to get is a litter tray though. The corner litter trays work well. You put it where the hamster decides to pee. Which is often a corner of the cage. With sand in. Although the sand is a bit expensive, it lasts a very long time. Needs to be the right type of sand! Any sand sold for hamsters is usually ok. So then the sand soaks up the pee and you just empty the litter tray once or twice a week. Most Syrians will use a litter tray - but only if you put it in the place they've decided is a toilet! It keeps the cage clean and dry and then it doesn't need cleaning out much. It's only their pee that is unhygienic. Aside from that they are really quite clean little things and like doing a bit of housekeeping themselves - refurbishing their nest etc.
You don't need to worry about poops really. They are not dirty or smelly. They're like little hard seeds. Sometimes they actually eat them (which is normal). They have two stomachs and can redigest nutrients etc from their poops! So unless they start taking over the cage, don't worry about them and then you can just pick them out/spot clean them out.
Cleaning is a whole other topic. But basically - you don't need to do big weekly clean outs. The more bedding you have, the less often you clean out and you mainly just need to spot clean (ie take out the odd handful of substrate and replace it with a new handful).
Big clean outs really stress them. So partial ones are better (ie don't clean everything at the same time). Using a litter tray minimises the need for it too.
Baby hamsters will sometimes pee in their nest though, until they get into more grown up habits - so then that area does need cleaning out a bit, but it's best to try and leave a little bit of the old nest behind (with their scent on) that's dry - even if it's slightly whiffy. And the same with their hoards. Best to leave their hoards along (they can be left quite a long time), unless they've peed on it as well. Then it needs removing. But then you need to put a handful of new food back where the old hoard was. They can get REALLY upset if their hoard disappears - replacing it helps settle that.
Anyway these corner toilets are inexpensive and work well. One of mine was very neat and used to pee in the very back corner then sit in the front part and have a wash.
Trixie corner toilet
For sand, either of these are ok. Not cheap but it's quite a big bag
Sand 1
Sand 2
Welcome to the forum! Yes, that would be a lovely, spacious cage with plenty of enrichment for rats and mice as they love to climb (signalled by their long tails) but hamsters traded their tails for burrowing (although Chinese hamsters still have some remaining tail) and although they can climb if they really want to, tend to fall heavily, unlike rats and mice, who are more agile. Hamsters really know how to dig though and can create huge burrowing systems with their immense energy. 
if you are looking for furniture. But hamsters will live quite happily in cardboard boxes and will customise things like Quaker Oats boxes to their liking with great enthusiasm 
