I’ve looked at all the videos. She is in every one, coming out not going in, and the timing is the same on every one. She probably went into the store during the missing 13 minutes which is also when that car pulls in behind Floyd’s. When she comes out of the store the car pulls away, does the u-turn, then parks across the street where she meets it and gets in. Probably so the woman does not have to walk over to where all this is happening.
I think these were just people who happened to be there and stuck around for a little while to see what was happening. It’s most likely their neighborhood store where they go often.
I checked out what you noted again and it’s even more pronounced than I remembered - the car starts moving to drive across the street second(s) *before* the lady comes out of the store and the “Park Police” car then takes its place. That is indisputably the car that #FakeNews CBS used in their report.