We received some feedback from some of our users that when they try to use Screen Mirroring, they will get a reminder message ask them to tap "Start now" on the phone and checked "Don't show again". But the fact is that they can't find the "Don't show again" option on the phone.
Kindly note that Google removed the "Don't show again" option from Android OS 10. It is an Android system option instead of an AirDroid Personal option.
So, if you are running Android 10, you can ignore the "Don't show again" reminder message and tap "Start now" on your phone. Then, you can mirror your phone's screen with AirDroid Personal. But you have to tap the “Start now” every time until Google puts the "Don't show again" option back.