I use a 6 stage Isprings https://www.amazon.com/iSpring-RCC7AK-Capacity-Drinking-Remineralization/dp/B005LJ8EXU
Tho I will say I use the remineralization stage for taste. While water can supply some of your DV of minerals its typically a very small amount. With an unbalanced diet you should be more concerned about the vitamins required for mineral absorption than the minerals themselves. Not enough D3 you won't absorb Ca effectively, not enough folate and your iron absorption is poor and so on and so on.
I bought mine off Amazon and installed it myself watching Youtube videos. https://www.amazon.com/dp/B005LJ8EXU/
You can certainly take them with you when you move. As far as what your complex allows, I'm not sure on that one since I live in a house. You can get reverse osmosis water from grocery stores too, though. Just buy a 5 gallon jug and water cooler, they have those on amazon or at walmart, and you can fill them up at the grocery store for like a dollar.
It does have a tank. But honestly you need a tank to get the time you need to go through the system especially with such a large bypass ratio.
But IMO a great system and great tasting
We bought one of these two years ago and it's been great....
https://www.amazon.com/gp/product/B005LKKMYS
This replaced an old Kenmore RO system from Sears that was installed in 2003. The iSpring unit has a mineral cartridge to add back in some of the stuff plain RO systems strip out and that's been a plus. You could definitely taste the difference and even feel the difference in your mouth. I guess it's supposed to be better for you to have those minerals in the water.
We live in an area with really poor water pressure (40 psi on a good day) which makes the RO system less efficient and take longer to refill the tank. If you have decent pressure the same system without the pump is much cheaper....
https://www.amazon.com/iSpring-RCC7AK-Capacity-Drinking-Remineralization/dp/B005LJ8EXU
Since we already had an RO system I didn't have to drill a hole in the sink for the faucet. The rest of the install is pretty easy for anyone with a few common hand tools and who can watch and learn from a YouTube video or two.