I need to create a simplified workflow similar to this picture for 3 courses
https://www.dropbox.com/s/2b2cvbyb6hwl3c2/cursos-onpe-ingl%C3%A9s.png?dl=0
and was wondering if Moodle can work for this task or if it is a kind of boxed solution.
PS: I am currently using Moodle 3.4
In the workflow I mentioned before I also need to crosscheck the identity of the users that want to register in my courses
against an external webservice that will validate their official ID document, so I wanted to ask you where should I start to accomplish this task
What this looks like depends on the details. That is, exactly what you mean by "crosscheck" and "official ID document".
However, if you "simply" want to restrict or allow access to an entire Moodle course you would need to develop a custom enrolment plugin that queries the external service. There are plenty of existing enrolment plugins to use as a reference. Pick the closest one, copy and go from there.
It will definitely require some coding though.
I need to validate is they are "real" IDs and detect the group they belong to (A, B or C)
depending on this they will be allowed to sign up.
Well, again, Moodle doesn't have a thing called "sign up". But regardless, you will be talking about a custom enrolment plugin or a custom authentication plugin. You need a Moodle developer.
Yes - check Restrict_access and Activity_completion
