Welcome to the Apple Support Communities. From your post, I understand you're trying to download music from iTunes that you have previously purchased, but find that the content is greyed out and not able to download. I'm happy to help!
There are actually a few different reasons you may be seeing those songs greyed out, as outlined below from About iCloud Music Library icons and status - Apple Support :
If your songs appear in light gray text
Your songs might appear in iTunes in light gray text for a variety of reasons. Those reasons include:
- You're not connected to iCloud Music Library. If you see a Disconnected icon in the upper-right corner of iTunes, you're not connected to iCloud Music Library. Click the icon to reconnect.
- The song isn't in Apple Music or isn't available in your current country or region. These songs also appear in gray if you search for them in Apple Music.
- Restrictions are turned on for explicit tracks. Learn more about Restrictions.
- An artist or content provider made changes or edits to an album. You might need to remove the album from your library and add it back from the Apple Music catalog.
More information can be found in the "If some of your songs are missing or the song names appear in gray text" section of Get help with iCloud Music Library - Apple Support , as well:
If some of your songs are missing or the song names appear in gray text
If songs that you bought are missing or the song names appear in gray text, they might use digital rights management (DRM). You need to authorize your computer before you can play these songs.
After you authorize, choose File > Library > Update iCloud Music Library from the menu bar at the top of your computer screen or the top of the iTunes window.
If you synced the songs that appear with gray text to your iOS device from a Mac or PC, turn on iCloud Music Library on that computer and your library should update.
Should you still need help, or have additional questions, about the greyed content, please reach out to Apple Support directly: Contact Apple Support .
Have a great day!