not sure what your brand of adhesive say on the instructions but I would usually screw a WBP plywood sheet 12-15mm down on top of your floorboards, screwing at 150mm centres into the floor joists. (screws need to be long enough to go through both plywood and floor boards). There might be proprietary baords you can use instead of ply- aquaboard, although I have no experience using that myself.
Don’t know if what I said is common practice but that’s what i’ve done in the past, and is what i’ve seen professional tilers do and have had no issues with cracking or loose tiles.
edit: make sure you evenly spread the adhesive without any voids