There's a Membership 2 Pro and an Events+ plugin running on the site where users are supposed to be able to add events from the front-end. That works if a font-end editing extension is enabled in Events+. Then the "Capabilities" extension of a plugin is used to allow only "Contributors" to add the events, which is fine too.
This, however, should be connected with a Membership 2 Pro plugin in that way that users that sign up for a specific membership are given a contributor role (or capabilities). Unfortunately, the "Membership Capabilities" add-on of Membership 2 Pro doesn't work in this case.
How to make it so that when a user signs up for a specified membership, he/she is automatically given a "contributor" role?