Use the .exe file in your Nextcloud account VPN Files folder.

1. Run the program OpenVPN GUI.
2. Once running, you'll find a new OpenVPN icon in the system tray. The red icon shows that you'r not connected.
3. To connect, right click the OpenVPN button, choose the network (usually vpn-citius but it may be different), and press Connect.
4. A window to introduce your CITIUS credentials will pop up.
5. To disconnect, right click again the OpenVPN icon, choose the appropriate connection and press Disconnect: