I don’t get it, do Autistic people follow the one big arrow, or the many little arrows, and which is correct and which is wrong, or does it depend on some other mysterious context?

Just follow the very obvious arrow, it’s not that hard

Since you say arrow singular, I can deduce that you mean the large arrow.

Which raises the question what purpose do the smaller arrows serve?

Each of the small arrows are individually obvious.

Pick the right one.