This issue happens when there is other VPN running in your Android phone.
Please:
1. Close all the VPNs that are running in the background.
2. Take a look at your device's settings: System Settings > Network > VPN, and check if the "Always-on" button is enabled in other VPN applications. Turn it off like this:
3. Relaunch the VPN and authorize as guided.
If the issue persists, contact us via Livechat.