There have been recent untested changes and additions. Log an issue as needed or sponsor a WHMCS testing license / server, if you like.
I have worked on this project for a very long time. In that time I have modified many versions of this module, made by others(for clients). In that process, some logic just worked better, so I adopted it. for example:
The date_range and freeradius_username functions are from the freeRADIUS module made by WHMCS, I think. I was previously using MySQL for the date ranges and returning errors on duplicate usernames. These just work better.
Copy: freeradius.php & clientarea.tpl file -> WHMCSROOT/modules/servers/freeradius/
Copy: freeradiusapi.php -> WHMCSROOT/include/api/
The reset of the files are for the radius servers.
cron.php is to be added as a cron job.
config.php.example is to be renamed to config.php and edited as per your setup