Hey pb134,
Thanks for using Apple Support Communities! We understand you're experiencing an issue downloading your music. we definitely want to make sure you're able to have all your music available, and we're happy to help.
We would like to have restart your device and then test if the same issue continues after restarting. Use the steps here: Restart your iPhone
If the issue does continue after restarting, updating your device is another good step that can resolve issues like you're experiencing. Check out how to do that here: Update your iPhone, iPad, or iPod touch
If that doesn't help, or your device is already updated try using a different Wi-Fi, and let us know if that makes a difference. We'll go from there.
Thanks again, and have a great day!