That should be something you can set up! But, make sure you are careful with what you mean by "add users". You could be talking about creating new user accounts on the site, or enrolling a user in a course.
I think, based on your description and second screenshot, that you want certain people in a course to be able to add other people to that course. In that case, you should look at the "enrol" capabilities, like enrol/manual:enrol and enrol/manual:manage. This role would need to be assigned at the course context. Take a look at the capabilities section at the bottom of this page to make sure the role can do everything it needs to do: https://docs.moodle.org/311/en/Manual_enrolment#Manual_enrolment_capabilities
You mentioned the "moodle:user/create" capability, which is for people to be able to create new user accounts. If you want the enrollment officer to be able to do this, then add this capability to a role which they are assigned at the system context (Site administration > Users > Permissions > Assign system roles).
I think, based on your description and second screenshot, that you want certain people in a course to be able to add other people to that course. In that case, you should look at the "enrol" capabilities, like enrol/manual:enrol and enrol/manual:manage. This role would need to be assigned at the course context. Take a look at the capabilities section at the bottom of this page to make sure the role can do everything it needs to do: https://docs.moodle.org/311/en/Manual_enrolment#Manual_enrolment_capabilities
You mentioned the "moodle:user/create" capability, which is for people to be able to create new user accounts. If you want the enrollment officer to be able to do this, then add this capability to a role which they are assigned at the system context (Site administration > Users > Permissions > Assign system roles).