No, your collaborator does not have to be on paid plan to access and edit your document.
However, your collaborator will have restrictions of the basic plan such as 1000 word export limit, no access to Plagiarism Check, etc.
For more information on the basic plan, check out the pricing page on www.typeset.io/pricing
Have questions, concerns or suggestions? Write to us at firstname.lastname@example.org or talk to us on Chat.