To my knowledge you just pay for the visa with a credit card at the passport control counter.
I don't know what the procedure is with the meet and greet service.
I personally know of a friend's daughter (Canadian) in her twenties who had a problem on arrival. Sometimes they suspect young single women arriving alone are prostitutes. She had to phone her parents who had to intervene in order to allow her into the country. So this young woman should make sure she can provide the passport control officer the name and address of her hosts and she should have the phone number of her host,just in case. Other young women, my own daughter included, have not had this problem.