1. Open https://vpn.ac/ovpn/
2. Download the file ca.crt
3. Open chrome://settings/certificates and import the downloaded ca.crt certificate under Authorities; don't check any of the 3 available options
4. Open Settings > Add Connection > OpenVPN
5. Add the following VPN parameters:

Server hostname: from the list at https://vpn.ac/status such as ro1.vpn.ac
Service name: any description
Provider type: OpenVPN
Server CA Certificate: VPN.AC [VPN.AC]
Username: your VPN username (e.g. vpn123456789)
Password: VPN password