iTunes 12.7 how to download all music from iTunes Match
If you need to download the already uploaded music to the iCloud (iTunes Match), you could try re-syncing the media library.


Step1 : sign out from iTunes 
Step 2 : Delete all the remaining music files.
Step 3 : Sign in to the iTunes.
Step 4 : Let it to sync the music library from iCloud.

For more info : https://discussions.apple.com/thread/8046575