The operation guide on the website is really not easy to use
1. The difference between openvpn and openvpn access server
openvpn is open source and free, but the setup is very complicated. openvpn access server is web ui setting, 2 user are free, multiple people charge
2. It is recommended that you buy a cheap cloud server to learn
If you install it on your own computer and need Internet ip and port, you need to open the port on the router.
Or you can install Oracle VM VirtualBox to install openvpn access server, learn some simple passwords and user profile to use
3. openvpn consists of two parts, the server and the client
For installation and use, it is recommended that you go to the website to check more information
https://openvpn.net/