What makes a Qiraat mutawatir?

Selam aleikum, I know, that one of the criteria’s of an accepted Qiraat is being mutawatir. (Ibn Al-Jazaris conditions) What exactly is meant with it and how many people are needed to make it mutawatir (in each generation)? So let’s say, there is a specific harf or some Ahruf in the recitation of the Prophet (saw), so he recited it and the companions heard it and then they learned it. Does this condition mean, that every single harf were heard by many companions (What number of companions is enough?) and then a Qiraat were made out of them and were recited by companions. Or Does this „mutawatir“ condition is counted after the forming of a Qiraat? Can someone clarify this. May Allah bless you.