This is actually a bug of the Windows Store, not a Maps Pro bug.
To fix this issue, some users just changed the settings in Windows 10 not to download/save anything to SD-Card and it fixed the issue they were having with the Windows Store.
To change the default storage, go to Windows Settings > System > Storage > Save Locations > New apps will save to > and pick one of your hard drive.
You can also try these options
Also try Windows+R, then type:
If it all fails, your best bet is the Microsoft support:
If you are still running into issues, please email firstname.lastname@example.org