I'm completely new to drupal and actually building a charity community site on Drupal 8.
I have a content type "PROJECT" with a field "PROJECT MEMBERS" as entity reference to "USER".
Now I would like to have a button on the display of any project node "REGISTER ME FOR THIS PROJECT".
If an authenticated user clicks on that button his name should be added as new Project Member Element in my node.
Is there any way to do this ? Thank you so much !