I used to download MP3s from a variety of sources but now I have upgraded my Mac to Catalina new stuff just doesn't play. Anyone got any ideas? Geoff

I might be talking out of my posterior, but I think the issue is that Catelina no longer supports 32 bit apps. I downloaded this last night and found some apps like bbc I player no longer work. I think there’s a workaround solution, but I haven’t looked at this yet. So, it maybe the change to 64 bit is causing this issue ref mp3.
Total guess and theory from my part...but if you google Mac Catelina review and then click on the MacWorld review this may be of use.