Apple Devices Windows-10 sync/backup

I use Apple devices app on Windows 10 to sync and backup my iPhone to my PC.

1. What does the Apple devices Windows app backup?
2. After I sync/backup using Apple devices my Music library is not updated in the Apple devices app list. It's missing recently purchased songs. These songs do however show up in my Apple Music app on my PC and on my iPhone, just not in the Apple devices app.
3. I'm using Apple devices, Apple Music, Apple TV apps on my PC because iTunes no longer supports sync and backup to a Windows PC. All that iTunes does is backup Podcasts