Coursepress Pro Shortcode for css class

Hi. I'm trying to apply a new css to the Enroll Button. I don't want it to apply to all the Enroll/Sign Up buttons, only a few so I am using the shortcode for the button (on a custom course page). See here: https://school.inlpcenter.org/4114-2/
I can't get it to grab the css I set up. Is there something I'm missing? In the shortcode I include class="enjoy-css" but it doesn't not find it.
[course_join_button course_id="3946" signup_text="Buy Now to Enroll in this Course" class="enjoy-css"]
I have the .enjoy-css in a custom css and js plugin. Is there something more I need to do? I have also tried to put .enjoy-css in the css files but apparently can't find the right one.

Also, one more question-
How can I change the text on the enrollment process popup so it doesn't just say "Sign Up" but says, "Create your student account first"?
Thanks!