How to give a roll only access to add a certain content type? In D8:
I have a content type call fooCT.
I have a role called:  "fooRole"

I give fooRole the following permissions:


fooCT: create fooCT
use simple editor


So the checkbox: View published content is not checked

A person with this role cannot do anything in the system anymore.

How to give this person only access to add a a fooCT?

I tried several options but do not get the desired result.

Any suggestion?
The Permission View published content is very important, without the users of that role won't be able to see Published content. What do you mean by "cannot do anything in the system anymore"? 

Do you want that Role to be able to create new nodes of that type, but not to be able to View those nodes once they're created? 

You should look into the Editorial Workflow, and Content Access module.