How to solve the problem of unable to click "OK" when setting up VPN connection?

While using FlyVPN Android version for the first time, you need to set up a "VPN connection". If there is a mask layer set by other software on your device, the "OK" button for obtaining VPN authorization may not be available.
The mask layer may, but is not limited to, be used for eye protection or floating windows. If you cannot click "OK", please check and turn off similar functions.
The specific solutions are as follows:
1. Close Traffic Package or the eye protection software.
2. Close the shortcut window or bubble floating on the phone screen.
3. Restart the phone.