Hi! Let me help you. Have you tried disabling Secure Boot on your machine?
Please follow the steps below to disable Secure Boot;
Press and hold the SHIFT key, then go to Start > Power > Restart.
Keep holding SHIFT until the system begins to restart.
Once your computer restarts, select Troubleshoot, then Advanced options, and choose UEFI Firmware Settings. Inside the BIOS/UEFI setup, find the Secure Boot setting and change it to Disabled.
This option is commonly located under Boot, Security, or sometimes Advanced settings, depending on your device. Save your changes and exit the BIOS/UEFI menu.
Your computer will restart normally into Windows.
After completing these steps, your system should no longer be in S Mode, allowing you to install and run applications from outside the Microsoft Store.