You should post a screenshot of “expanded” configurations of Triggers and Actions, this view doesn’t provide any information that might help people here with the problem.
Also when you say you cant enable automation, do you get any error or? That might also be useful.
Personally I haven’t used this action yet, but my guess here is that it requires you to enter end date also, and that is why it is thinking your configuration is incomplete (which kinda makes sense since it wouldn’t know when your event will end otherwise).
I don’t see anything else that could be problem.
Did you manage to run test on action part also?