Some clothes washers do require the elevated location of the top of the discharge hose. Lowering it to floor level typically drains the machine and the pump-- very useful when preparing to store the machine in an unheated area. While HUD code did/does (?) provide for 1 1/2" washer drain line, regular plumbing codes have for many years required 2" for washers. Dumping into the shower pan may not let the water flow out of the pan as fast as the washer discharges it.
I too have had to live with temporary arrangements while occupying rental housing. We used the kitchen sink. for the washer drain.

Most shower drans are coverd with a strainer that can easiely clog from lint. If yours is removable,I would place the hose directly in the drain. Otherwse I would keep a close watch while washr drans,and/or clean the screen between drain cycles.

The drain hose must be elevated to loop up higher than the highest the water fill level reaches in the machine to avoid siphoning and gravity.

Many thanks. I realise now that the waste pipe has to be a certain height so that's fine. My shower that is 30cm deep so should be able to handle the volume of water.