First you should read the readme
Next, after you connect to a server and the "LED" light blinks (orange-lightorange),
go to GTA3 and start an MTA game, alt+tab back into MTA and click Send Game Request button, alt+tab back into GTA 3 and wait a bit, the credits
should go away and you will be able to pick your team.
Note: You should pick diablo because of known problems with mafia...
Note2: I have to do the whole process over again (twice) to get players to show up and stuff, dunno if its just me
Good luck