List Categories into Registration Form and assign to user automatically

I'm using a wordpress plugin "WPCourses Pro" http://goo.gl/YaIp3K. Free version is here http://ift.tt/1z3e3HA

The plugin has taxonomy=category_course and post_type=courses

Selling Courses are done through WooCommerce

What I need is the following

Create a custom registration page with extra meta user fields like First and Last Name and other fields but also what we're looking for is to add an optional field for the student to choose the course he wanna enroll.

Like choosing when choosing

Main category it will automatically loading sub-category then when choosing sub-category it will load the Product SKU example.

When choosing: - IT Academy (it will load) --- Cisco --- Microsoft

When choosing Cisco it will load

---------- IT Essentials

The student/registrant has the option to choose IT Essentials once this is selected it will automatically be assigned to his account.

How this can be obtained? Can you help me please!

Thank you so much!