A tutor you already work with may send a link to add your details, or a link in an email to hand in work. Neither needs an account.
A link to add your details
A short form: the student's name and an email, and anything else you'd like the tutor to know. It puts you on that tutor's student list and nothing more.
A link to hand in work
Opens the work your tutor set, so you can hand it in and read what comes back. It reaches that work and your progress updates, nothing else.
Making an account later with the same email links you to that tutor, and gives you messages, reminders and online booking. Work you handed in through a link stays on that link.