Upon your initial attempt to access one of these subscription sources, you should be prompted to login by the proxy server with two-factor authenticationonce each browser session. If you close your browser, you'll have to log in again the next time you try to access a licensed resource.
Note about VPN:
A VPN essentially treats your connection as if you are working on campus. So, you should not have to login to proxy server to access the subscription resources.
However...If you are having access problems while using your VPN connection, try disconnecting and switching over to a standard internet connection, and then login to proxy server.
You may then reconnect your VPN if desired, and your proxy access to WU Libraries resources should remain active.