ICloud Drive: Cannot download files

I know it may be a little too late to answer but, if you haven't found out a way to get all of your photos to your ICloud, here I how:

You must transfer all photos from PC to Iphone through ITunes. You should have a photos tab that you can select after connecting phone to pc. You must check the box that say sync photos and make sure you select the radio button where you can pick which folders you want transferred over. Unless you want your WHOLE library. After you sync your photos, create a new album on your phone and SAVE those photos to it.

Icloud photo library will only upload photos that were TAKEN or SAVED to the phone. Once you save your photos, go ahead and use icloud photo library to upload those photos to Icloud. To view among all devices, make sure Upload to My Photo Stream is on. If you want to share photos, make sure ICloud Photo Sharing is on.

Im a Technical Lead for a well known cellular company and have done my own research, troubleshooting, and testing to confirm this information.

Found a kind of workaround to re-upload those related songs. Make sure you have a backup of those songs before trying in case something will go wrong, and make sure you have exported your custom created playlists to import them later if any of those songs are there.

You are going to remove those Matched or Purchased kind of files and will create new ones. These steps should save all the metadata like ratings, play counts and so on, but will have a new one date added to library.

iCloud should have to check those files again and will make those songs Matched or Uploaded once again, but this time everything should be playable and downloadable for offline use.

Make sure you have the iTunes Plus setting in Preferences > Import Settings. Create the new playlist and put all songs you found broken in your previously created Smart Playlist, just in case it will not mess up later. Create a new Smart Playlist with todays Date Added, this will put all fixed files there that you will create later.

In the next step you have to Create AAC version in File > Convert. This will make a duplicate file but all the crucial metadata should be the same, file size may be larger or smaller though.

Now you need to completely remove broken songs under Song > Delete From Library.

This will give new Removed iCloud status to the newly created files. You will need to select all files in the new Smart Playlist with Date added today setting, right-click and select Add to iCloud Music Library.

You will have now Matched or Uploaded iCloud status in these files but everything should work properly now. The location of files eventually should be the same as removed ones, so you can have playable Exported playlists that you want to Import now.