On Apple silicon-based Macs, system extensions are blocked by default. The system extensions will need to be enabled in MacOS recovery mode by following the steps below.
The following message will appear in System Preferences -> Privacy & Security during the installation of Desktop App. To allow the kernel extension in Desktop App. Click the Unlock icon if needed.
Then click the “Enable system extensions…” then select "Not Now."
You will now need to go to the Recovery environment to enable system extensions. To do so, Shutdown the system. Turn the machine back on by pressing and holding the Touch ID or Power Button to boot in Recovery mode. Select Options and click Continue.
After this, the following menu will appear
Click on Utilities from the menu bar → Startup Security Utilities
Select the drive where DesktopApp is supposed to be installed. Click on the Security Policy... button
In the window that appears afterward, the Reduced Security setting needs to be selected. Then check the Allow user management of kernel extensions from identified developers. Click OK to save your new startup settings. Then restart your machine.
The following warning will appear again. Click on Open Security Preferences.
(If the warning does not show up, go to System Preferences -> Security & Privacy)
Click on the lock icon at the bottom left corner and make sure that it gets unlocked. Enter the admin password when prompted.
Accept the kernel extensions in the System Preferences -> Security & Privacy.
Another restart of the machine will be required after the last change. After restarting, the user will be able to use Desktop App in macOS BigSur.
Further Troubleshooting Steps:
If this guide did not help to resolve your issue, please follow the steps in Desktop App M1 silicon support (additional problems)
More info about Installing a Custom Kernel Extension on Apple's website: https://developer.apple.com/documentation/apple_silicon/installing_a_custom_kernel_extension