Can I put a 8 speed bike on a Elite Suito 11 speed direct drive turbo trainer

I have recently ordered an Elite Suito Direct Drive FE-C turbo trainer. The main use is for indoor, winter cross-training for my young son who’s a keen athlete (we don’t want to send him out in the dark on his own and I can’t keep up with him any more) but I and my wife would like to use it too and we’d all like to use the same bike on the trainer. The tentative plan is to put my wife’s step-through Dawes Discovery 301 hybrid bike on the trainer, as the frame is small enough for my son to manage and just about big enough for me (I might need to put a longer seat post in), so no frame swapping would be required.

The Dawes 301 has 8 cogs/sprockets at the back and 3 at the front, i.e. 24 speed. From a bit of googling, the rear cog (cassette?) on the bike may be a Shimano CS-HG30 11-30T, the rear wheel hub a Shimano FH-RM60 36H QR and the front cog (crankset?) a Shimano FC-M191 48/38/28T.

The specs for Elite Suito trainer include the following info:

• "Compatible with 9, 10 and 11-speed Shimano and SRAM cassettes (not included), can be adapted for Campagnolo using adaptor TT14233 or SRAM XDR using adaptor TT14279"
• "Compatible with 130 and 135 mm quick-release frames as well as 142 x 12 mm thru-axles, adaptors for BOOST 148 x 12 frames are available separately"

My question is, can I use this Dawes bike frame with the Elite Suito trainer and if so, what is the best way of doing this? For example:

• can I take the 8 speed cog off the back wheel of the bike and use it to replace the 11 speed one that is supplied with the trainer; I’m guessing not because the trainer specs say it’s only compatible with 9,10, or 11 speed cassettes but is there a workaround?
• if not, what is likely to be the cheapest solution to get a basic, mid-size frame up and running with the trainer, e.g. would I need to swap out all of the drivetrain on the Dawes bike (front and rear cogs, front and rear derailleurs, shifters, chain) and if so, would it be cheaper to buy a compatible 2nd hand bike instead (if yes, what specs am I looking for)?

Apologies if my terminology is incorrect but I know virtually nothing about the technicalities of bike design and maintenance, as you can probably tell. Thanks in advance.