vpn.rbx.com is used for getting into the internal Roblox network. They use Paloalto Networks and Okta to operate the website.

Too lazy to put the rest, so just find it in the wiki's GitHub https://github.com/itsnotskeletonbuildsbricks/robloxwiki

Okta: https://rbx.okta.com/app/panw_globalprotect/exk1jvuc6vrMirlHO0h8/sso/saml