Here is what I interpret it as.
I am a big loser with a small penis who was asked to post this ad for my parents apartment that they own. I am looking for a girl to rent this place but if you just look like a female that is also fine. I just want someone who is actually gonna open the door when I come collect my rent. I want you to weigh no more then 118 lbs because that is what I weigh and I am afraid if you weigh more then me I will get beat up when I come to collect the rent. I hope we have chemistry if we do I won't even charge you to live there. If you have no job it is okay we can work out a deal on the rent.