I had some trouble at first with that as well but after respawing for like the 3rd time or so I noticed that I had been getting quite a few weapon drops from the ones I had defeated before we got overwhelmed. I stopped for a minute and outfitted the rest of my away team with these nifty new guns (as opposed to their basic phaser pistols they started with...except my Tac officer anyway) and WOW what a difference. Be sure to look out for a weapons locker in one the side rooms, there's a bunch of free weapons in there that are pretty awesome. Dunno if it's random or preset, but I ended up being able to breeze thru once I had my team outfitted a little better.
SO tl:dr version is outfit your team better and you'll have no problems and you can even do so once you get there if you are like me and hadn't done much ground before doing it or have money to buy weapons.
it is not that hard, but you need to focus certian mobs,
to kill first in roughly this order:
Sword masters (they kill fast up close)
Targ handler (They keep spawning targs annoying as hell slows you down whihc means respawns catch up with you)
Muntions master (just to get rid of the knockdowns, he is not that dangerous tbh)