Vpn connection issue with GL-AR750

I have just bought a GL-AR750 VPN router.
I would like to set up my VPN but no luck.
I have tried with NAMECHEAP VPN and IPVANISH both .ovpn file import with success but the connection always fails. i have download NCVPN-UK-London-TCP.ovpn and imported with success and error log as below.

Control Channel: TLSv1.2, cipher TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 2048 bit RSA

[vpn] Peer Connection Initiated with [AF_INET]


AUTH: Received control message: AUTH_FAILED

SIGTERM[soft,auth-failure] received, process exiting

VPN client failed to connect. This may be because of wrong configuration, unsupported parameters or terminated by the server. Please choose another VPN profile or abort the connection.

I will appreciate your help.
Kind regards

Pls refer to this video guide How to Configure OpenVPN on GL.iNet Routers - YouTube

You need to upload the cert etc. in one zip.