They were forced to give Microsoft exclusive access, because it was one of the terms of Microsoft's billion-dollar cloud credit investment.

But you can't pay employees with cloud credits, so time will tell whether it was a correct decision. (It probably was. And I exaggerate slightly; the investment included a substantial sum of real dollars too. But most people see that billion dollar investment and think it's all dollars, when in fact it was largely credits.)

Is that only for GPT-3? Or for everything they produce?

I don't know for certain, but it was probably everything. The investment was vital.