You'll need to know what the TX frequency is i.e. 433MHz, 315MHz, 372MHz etc. It's best to know the make/model of the opener. Or take the remote apart and read the PCB. Or recognize the remote's unique shape.
Rolling code was conquered a long time ago.
I got a replacement (rolling code) remote from Ali
GATE-RC9 Store cheap and works great. You have to pair it with the opener, otherwise it is ignored.
But for a many remote apartment complex, I would think it is not rolling code.
In that case look at Linx Technologies bought out by
TE Connectivity I got their stuff from DigiKey, it's better quality and more expensive.
If the remotes (all) have a simple common address, it does make it hard to manage - imagine rejecting a remote that was lost or stolen without redoing (pairing) it for everyone - because the RX typically can only "erase all" learned remotes and you have to re-pair for all of them...
Ali does have low cost remotes and receiver modules that are multi-band and do both rolling or fixed code like this
RX module.