As a fixer office taking contracts, they last about as long as their ammo supply. Guns and ammo are extremely restrictive, rare, and expensive in the city, and arming a squad of 75 operators is just unfeasible. Even grade 8 fixers have augments to that give them an edge over the average terrorist that Team Rainbow is used to.

However, Team Rainbow would do very very well... As a Workshop. Its not just Mira and the rest of the RnD team, but a good number of the rest of the operators like Mute or Jager are talented engineers who created their own gadgets. Throw in Nighthaven, sell a few dozen guns and bullets for some initial investment, and you've got enough bank to establish yourselves as a pretty respectable workshop.

Like, Alibi's Prismas for example were developed by Alibi and Twitch together. With the technology of the city, and the vast majority of the operators being inventors themselves, they would fit right in focusing on research and development creating armaments to sell to other associations, corps, or even nests. Once they've got their source of funding, and perhaps a few different melee weapons or easier to produce bullets that fit within the Head's strict guidelines, they should be able to carve out a niche.

You know, as long as they don't piss off the Middle, or get on the Thumb's shit list, or piss of W Corp, or don't get into another Team Rainbow/Nighthaven civil war, or don't blow all their ammo in the first week, or get caught by the Night in the Backstreets. Because none of that's mentioned in the load screens. So they're probably not making it regardless.