You’ll have to find a DRM stripping program.
What happens is it prompts you for the password and user name, they must be correct, and once you are past the DRM part. I don’t know if it just flat out strips the drm part off, or it just makes another file from whats inside the DRM.
But you most likely will have to unDRM the files before you can convert them.
for a good undrmer ( i love making up words) you’d have to google, and give a few test runs, I don’t have much experience with undrming music files, Just porno 