The VPN permission prompt
Android asks once to allow JustCoffee to set up a VPN connection. Every VPN app needs this.
The first time you connect, Android asks you to allow JustCoffee VPN to set up a VPN connection. Every VPN app needs this and it is asked once.
If you declined it, just connect again and Android will ask again. You can also manage it under Android Settings, Network, VPN.