Because now they don't have enough money... (to boost the server) the server was full from bots (from the boost) the server wasnt full of Ambrosian members, Sadly.
Not sure where you got that information about lacking money from but it's not true.
as i remember a guy (i forgot/mixed his name) has boosted the server b4 4 or 5 days, and it really went soo active but these last 2 days the server got empty i also dont understand why but i think boosting wont help a lot, only if we boost a lot, may be :/ and so whenever i join i only find 1 or 2 no more 
good luck finding a solution 
It didn't really get very active, multiple times it wouldn't go over 15 to 20 players and that even during peak hours. I'm not sure if it's due to the amount of download needed to join the server or another issue..
But anyway to be fair, the server is in a poor state and I feel like nothing's happening for it to change at the moment, perhaps it's because I'm used to another type of Zombie gameplay but I really don't like the whole "LM/Armor/Smoker" gameplay, it's too focused on camping and armor combined with LM make it hard for Zombies, leaving it only to bugging people through wall as a smoker to infect or stucking them in some place they can't shoot. If not for that then you've gotta bomb the person and to be honest, that's not fun at all.
Items are lackluster for the major part, those guns that cost a ton of AP aren't worth buying, they barely do stuff. As for other items, they're either broken / must buy or as said before, aren't worth using for its cost etc. The Forcefield shield being there for a whole round is stupid as heck but can easily be countered by a bomb (80AP spent to disappear easily, if you don't have AP for a bomb, have fun because the guy's unkillable), the "Infection Immunity" is there for really no reason almost since armor's there.
Could go on for a while still, but basically there's a lot that is wrong with the server and sorry to say but Ren0k asked for this server a lot but in the end I don't see him doing a whole lot currently. Be it fixing the balance or working towards getting the server popular. It's as if after a week, his whole motivation just went down the drain.