Why do I get the message "Your PC's settings only let it install verified apps from the Store?"
Computers that run the Windows 10 in S mode only allow you to install and run applications that can be downloaded from the Microsoft store. You will receive the error "Your PC's settings only let it install verified apps from the Store" if you try to install an app that was not downloaded from the store. You can switch your system out of Windows 10 S mode using the instructions that Microsoft provides for switching out of S mode in Windows 10.
Note: Once you switch out of Windows 10 in S mode, you will not be able to go back to Windows 10 in S mode.