If you want to run floor underneath the spa, you must have a permanent (glue/nail/staple/mortar) floor. A floating floor underneath an anchor like a small swimming pool = a floor that rips it self appart.

Normally flooring isn't needed underneath a permanent structure such as cabinets, hot tub or swimming pool.

This is inside? IMO you need a proper base usually concrete for this type of pool so maybe get someoent to istall this the right way.