Additional information:
I’ve done my task, Freeradius woks as it should, and wifi and pptp auth works fine to.
But now I’m faced with problem when I have to connect every username in Freeradius database with user’s IP or pool. I’ve found such information:
https://wiki.freeradius.org/guide/Ippool%20and%20radius%20clients
http://forum.mikrotik.com/t/mac-authentication-dhcp-radius/116818/6
http://www.netexpertise.eu/en/networking/freeradius/ip-pools.html
but I can’t understand how this schema works in general.