WordPress membership and scheduling help

I have created a website for a flight school in WordPress using Elementor Free and Essential Addons. Need help with:
3 roles, admin, instructor, student
Protect student account with password
Allow instructor to write assignments and discuss with student or “their page”

Login form does not work on site (used Essential Addons for register and login)

Need scheduling plugin set up so instructors can block out time when not available, students or general public can schedule time and pay for it; follow up emails, ability to cancel or change times.

I do not want to pay a yearly or monthly fee for the scheduling plugin; a one time purchase of a reasonable amount for this, or free.

I want a specific bid, no generic responses will be considered. The work is now. I want you to tell me how you would do this, what you would use, and be specific about time.