When I try to update my computer to Big Sur it says I need more memory.

Ok, go to the apple menu and select about this mac. a window will appear click on the storage tab. You should see Macintosh HD. And a manage button next to it. Click the manage button. That should bring up about a more detailed page of what sort of files are taking up your storage. Let me know what it says. If it is all music and you purchased from the Itunes music store you could delete the music files and re-download I believe. How much free space do you have left on your Machintosh HD?

Paul

You are out of disk space. Look at your hard drive "Macintosh HD" and see if there are any files that you can get rid of. Empty your trash (menu option in finder menu)

I hope this helps.

Paul