This app is probably not yet for you and will not work on your device. It requires support inside the your device's ROM. Talk to your device manufacturer or ROM creator about adding support for WireGuard. Or, check back later when we're ready to launch, and we'll support all devices.
This manages WireGuard tunnels for phones that have the WireGuard kernel component. Future versions will include a userspace implementation for supporting phones without the kernel component. Most likely your phone does not yet have the kernel component.