Once installed, the application must have full access to your Mac.
Otherwise, you may not see your desktop during remote sessions and/or you can't send commands with your mouse and keyboard.
Then go to System Preferences under "Security & Privacy"
Go under Accessibility and select SygmaConnect (click the lock at the bottom of the sx first to unlock the changes)
If you don't see it, go and add it manually using the
SygmaConnect is located in the Applications folder
Now navigate to "Screen Recording" and do the same.
That is, select SygmaConnect.
This will help you control your Mac remotely.