CAS WebFlow Extentions

[Modus Operandi]

Hello:

We need to display a page on authentication -- where if user is in an LDAP group --- will prompt them to register they device with Duo (users can select to be 'redirected to a registration site' or 'continue as usual').

I have read w.r.t extending the CAS webflows at https://apereo.github.io/cas/5.2.x/installation/Configuration-Management-Extensions.html

As there is so much to learn with CAS being new to us, wondering if anyone can point to an example extension with somewhat similar requirements?

Thanks.