Satanic explanation?

I just watched the movie "Satanic" on Netflix. I just didn't understand the end, for example why she sees herself in the parking garage at the beginning etc. Could someone please explain that to me?

She is caught in a circle due to joining Satanism. That's how I interpreted it. Why not know why. That certainly has a deeper meaning, but I don't really know about Satanism

Thanks,

Just don't quite understand why she saw herself in the beginning.