Hello, dear, install a master key on your mobile phone, which can be directly connected. Open the master key, search for the wifi name, and connect directly after finding it.

Or directly open the mobile phone wlan to search for the wifi name and connect. Generally, when you open the mobile browser after connecting, you will be prompted to do relevant authentication, and you can surf the Internet after authentication.

If you have a password, ask the librarian, and you will usually be told.