please confirm that i understand this correctly. You cannot transfer or copy I tunes music to a sansa device?

You cannot copy DRM protected media to a non-Apple device. Music purchased from the iTunes store before 2010 may be DRM protected, as will anything downloaded for offline use using the new Apple Music service. Anything else should be OK, assuming the Sansa can play AAC files.

Looking here https://en.wikipedia.org/wiki/SanDisk_Sansa it seems Sansa's support for AAC is patchy.

tt2

If you have song files from which you need to create MP3 versions, you can do the conversion with iTunes. Follow this guide:

iTunes: How to convert a song to a different file format

https://support.apple.com/en-gb/HT204310

As tt2 notes, the files must be non-protected for this to work.