Openvpn on ubuntu 18.04

[darkmanx07]

Hello,

I'm having some problems configuring openvpn on ubuntu 18.04, since i'm a noob when it comes to ubuntu i used 2 lines:
sudo apt install openvpn network-manager-openvpn
sudo apt install network-manager-openvpn-gnome
And now the problem is that when i try to add a new VPN i seleted user/pass/ and ca certificate problem is that on my laptop on windows i dont use ca certificate, i use user pass and client.ovpn (and it work's really well) and there is no option to select user, pass and client.ovpn only.
How can i accomplish this in ubuntu 18.04? I tried with ca certificate generated from router but i get some errors .
I need the easiest solution since i'm not familiarized with linux/ubuntu and i will need to configure 15+ laptops so they can work from home.
I used an Asus RT-AC68U router to create the VPN server.

[darkmanx07]

In case it helps, here is the log for when i try to connect using server CA:
https://imgur.com/nO5E32Q
And here is my router configuration for OpenVPN:
https://imgur.com/fNlHXtu