Sorry to hear that. For that issue, you can check this article on how you can reset your local administrator account password IF you remember the security questions you've input.
https://support.microsoft.com/help/4028457/wind...
If not, I suggest that you contact the shop and see if they can reset that for you.
For the issue above, you can try the troubleshooter and see if that won't ask for an admin account to proceed. That's in Windows Settings > Update & Security > Troubleshoot > Select Windows Store Apps then run the troubleshooter
Also, you can check if restarting the Windows Explorer would help. Press Ctrl + Shift + Esc to open the Task Manager. Under Processes tab, right-click on Windows Explorer then choose Restart
If those didn't work, unfortunately, most of the steps would require admin rights which we don't currently have at the moment.