Have recently updated to 188.8.131.52 and am no longer able to use any 3rd party Loops, the loops that work have to be "magix store" or "producer planet" just thought I would share, disappointing really );
I have the same problem.(2021 Version ) I can load them from the File manager but its a real ball ache. I prefer to use my extensive Cymatics collection as every sample is 100% royalty free and avoids any copyright issues https://cymatics.fm/ if you havent used them i recommend you check them out, Tonnes of free stuff on there.
Not sure why Magix have done this but its counter productive and extremely annoying
Assuming you are referring audio samples ie audio loops from Cymatics there is no other way of adding them to MMM - they do not appear as Soundpools.
If you have VST's, MMM 2021 has a bridge to allow use of 32 bit VST's, and as this is a complete new install as opposed to a straight patch, the old VST paths may have been cleared and they need adding again.