If you are seeing that the create student tab is grayed out when trying to add a new student, this is because some of the required fields are missing data. Once all of the fields have been filled in, the button will then be colored in and you will be able to create the new student.
In the image below, we can see that two fields are missing content. Class assignment and Grading Profile. Once these fields have been filled in, the Create student tab will be available to select.