freeRadius and google-authenticator: how do i get the qr code on a website?

I need to do a setup which I expected to be very common: Setup freeRadius, google-authenticator with an existing Active Directory to setup 2FA for Horizon View. Show the qr-code generated by google-authenticator on a website after user authenticated with his Windows-credentials. I found an ages old article on how to get this done on [archive.org](http://web.archive.org/web/20150509034720/http://vcdxorbust.com/totpcgi-and-freeradius-with-vmware-view/ ). Unfortunately, the package totp-cgi mentionned there does not exist on Debian AND depends on pam_url --which apparently I cannot build on Debian, and I have no idea if the needed packages still exist on newer versions of centOS. Displaying qr-codes on website should be problem someone has already solved. What am I missing?