Import the .ovpn config file into the VPN application of your device and connect!
By default, all the traffic of your device will go over the VPN.
If you don't want this, run
sudo snap set easy-openvpn-server push-default-gateway=False.
Changing the public address
The snap will do its best to figure out what the public address of the server is. However, when that fails, you can manually set the public address.
sudo snap set easy-openvpn-server public-address=example.com
The snap automatically creates a client profile and config with the name default. However, it's recommended to create a separate client profile for each user. This way, you can revoke the client profile when that user does not need access to the VPN anymore.
sudo easy-openvpn-server add-client alice
sudo easy-openvpn-server show-client alice > alice.ovpn
sudo easy-openvpn-server remove-client alice
By default the server runs on port 443/tcp (https) and 1194/udp (OpenVPN). If those ports are already used, you can change which ports the server runs on.
sudo snap set easy-openvpn-server udp-server.port=1234
sudo snap set easy-openvpn-server tcp-server.port=80