It used to be hard, now it's quick, and it works. This quick set of steps shows to install Reaper as fast as possible, as well as two free VST plugins - a clear synthesizer with useful presets, and a decent drum machine.
sudo apt install jack
/home/PlayOnLinux's virtual drives/drive_c/Program Files/VstPlugins
and the Steinberg folder too)I ignored anything online I found about wineasio because I couldn't get it to work.
I tried LMMS too but it couldn't run either plugin - they showed up as blank GUI boxes. And installing the Linux version of Helm seems pointless as all Linux DAWs run only Windows VSTs.