Do my users have to create an userecho account to "comment" the feedback?

Once I create a project, I want my customer to submit feedbacks, comments, ideas ...
They have to create an userecho account, instead of creating an account for a particular project.
After creating an userecho account, they are allowed to create their own project for example, however, I only want them to comments or leave a feedback
Is there a way to do that?
Hope this make sense
David