Download Google Photo from the App Store. Once finished installing, select it to open
Tap "Get Started"
Tap "OK" to allow Google to access your photos
Make sure the toggle is on for "Back up & sync", then tap "Continue"
Select "High quality - free unlimited storage", then tap "Continue"
Select "Allow" notifications
Tap the arrow
Tap the checkmark
Select "Assistant"
Wait for backup to complete (See box that says "Backing up photos") ***This may say 1(or different #) item left, but will often load more after, so make sure it's actually finished before you proceed!
Now verify that the box says "Backup complete" and it stays that way (sometimes it will load more items, so make sure you check the main photo screen that everything has uploaded/saved) Then click on the three bars (settings)
Select "Free up space"
Tap "REMOVE(#)" once you're sure you have everything saved
Now you have to leave this app (tap on the home button on your iPad) and go to the Apple Photos app
Go to your Albums and select "Recently Deleted"
Tap "Select"
Tap "Delete All"
Tap "Delete *#* Photo(s)" - your device storage should now have more space available
***You may also want to do a new backup to account for these items being deleted and update your iCloud storage*** (See the iCloud Backup page)