Unable to access 'Network Guest Access Page'

Do you know how to force open access page to login with my credentials?

I used this library access a month ago for the first time and it was working fine but after my passwork expired, I'm trying to login but the Login page is not opening. I've tried 'Forget Network' and DNS cache clean using 'sudo killall -HUP mDNSResponder'

What should I do?