[lms] Need help with auto invoice creation

Hello! Thanks guys for great product, I have managed to install LMS with freeradius to authentificate my pppoe clients, I have managed to get lms-fping to check node status and that is great so far. I am wondering, how could I get lms to generate invoices, it is very difficult to find any documentation in english. Also I would like some suggestions, how to get usage stats from mikrotik routers. Note, lms is not acting as gateway, so there is no customers traffic going trough.

Thanks!