Starbase 24 is basically an Energy Credit farming mission. You will eventually complete the mission, if you stick it out. You will also die a lot. Don;t let it bother, just respawn, fly back in, blow a few things up, die ... repeat.
The person who does the most overall damage gets the best reward, second most gets the second best reward etc.
I regularly win the 1st place rewards, and by necessity die endlessly doing it, since I have all the aggro.
IN summary, this mission is competitive between players rather than co-operative.
(as far as warping in to find the count already at xx/50, it happens all the time because the Que starts the mission without being sure all the spots are filled. It's darn near impossible to WIN the best rewards if you get in late, but that's just the breaks on that part sadly)((hint, if you que for it and the que pops immediately, you are probably about to be placed in a mission in progress. best to not accept that que and reset and wait for a fresh one if you actually want to win))
late response, but whatever.... Starbase 24 teaches you how to do STF's as a team. You go solo into tons of Klingons, then your burning hull is your lesson for the day. Fly with the team that you're with.