Hi elapid95,
It would be OK to put it on the floor for the short term but I would put a blanket underneath it to help protect the mattress from dust and stains.
A memory foam mattress will do best on a firm, evenly supportive, and non flexing support surface so if you have a box spring (that flexes) it would be better to use it on a non flexing surface like a platform bed or foundation (or in the short term the floor). If you have a non flexing foundation (vs a box spring) and it’s still in very good condition with a flat, non flexing surface with no sagging or soft spots then it would be OK to use it (see post #9 here).
Phoenix