To solve this problem, please make sure your device which installed AirScreen meets the following requirements below:
Please make sure the operating system below Android 8.0. （You cannot enable the Miracast in AirScreen on the device higher than Android 8.0, because Google removed the Miracast on Android systems above this version.）
Please make sure "Miracast" has enabled in AirScreen. (AirScreen -> Settings -> Miracast). Then, try to cast to AirScreen by the build-in Miracast.
Then, try to cast to AirScreen by the build-in Miracast.
If you would like to cast Windows 7/10 to AirScreen, please check wireless care meets Miracast compatibility requirements. We recommend that you install the Chrome browser on your Windows to cast your desktop. Refer to this video: Cast your Windows 10 computer to Android with Google Cast (Android TV)