On Server side
1. Log-in to your Unifi Gateway (Dream Machine, CloudKey, Server, etc.)
2. Go to Settings > VPN Server > OpenVPN
3. Create New > Click OpenVPN
4. Add user and Create password > Save
5. Download the Configuration File
6. Go to remote user's computer
Make sure that the config file is saved on the remote user's machine
7. Install OpenVPN on Remote user's machine
You may download the installer in: https://openvpn.net/client/client-connect-vpn-for-windows/
8. Once Downloaded, On the Profiles Tab, click the "+ symbol"
9. Upload the Config file
10. Then try to connect
11. Once connected, you will see below: