The plugin works just the same with freeradius 3.
The only difference is, that the configuration of freeradius 3 changed and you need to change the config file. Nothing else.
You can read into https://www.privacyidea.org/two-factor-authentication-with-otp-on-centos-7/
or it is simple as that:
https://github.com/privacyidea/FreeRADIUS/issues/11