Hi,
I'm Diego Rios, an Independent Advisor willing to help other Microsoft customers.
Try to open any browser, then log in to https://onedrive.live.com if you got any error messages let me know, if you can allow to access to your account and the app works properly when you play videos. Please, you can try the following troubleshoot below for the iOS devices:
Verified if the OneDrive is Update, If sync doesn't work, OneDrive is not launching or OneDrive is crashing, please try to re-install OneDrive:
Uninstall the OneDrive app by pressing and holding the OneDrive app icon. Tap the 'X' in the corner and then accept the confirmation message to delete it.
Perform a “soft reset” by pressing and holding both the Sleep/Wake and Home buttons simultaneously for at least 10 seconds, until you see the Apple logo. You can let go of both buttons after the Apple logo appears.
Reinstall the OneDrive app from the App Store.
Make sure that OneDrive is kept up-to-date by enabling it in your device's Settings > General > Background App Refresh.
You may find that enabling location services for OneDrive helps, especially if it’s during background sync. You can turn Location Services on or off at Settings > Privacy > Location Services.
Please let me know if this helped and works.
Best Regards,
Diego R.