Youtube to Mp3 file downloaded to iTunes not edited!

I am using an iMac running OS 10.13.6. Using a Youtube to Mp3 app., I downloaded a musical backing track to my Mac which opened in iTunes. When i tried to change the key and tempo using Audacity, I found that the file could not be edited. Any suggestions about how I can get these files edited by Audacity. Thanks

What do you mean “could not be edited”? How are you getting the file into Audacity?

– Bill