Setting up different roles during workflows

Hi all

I’m trying to implement a workflow with various approval stages with specific roles for each of these stages.
For a specific transition, I have enabled the permission for this role to transition the workflow instance but when impersonating that role and checking for that option on a document, I can’t find where to perform this action. Any idea how to unlock this?
I’m clearly missing something but I’ve tested so many ACLs on different levels that I’m afraid I’ve overcomplicated this.

Also, what would be the easiest way to set up the ACLs to have a document inserted by user A, that can then be transitioned only by user B and approved only by user C, for instance?

Thanks in advance!