I developed a billing reminder for freelancers. Where do you lose onboarding?

Freelancing for six years meant dealing with overdue payments for five and a half. And that is why I developed NudgeInvoice, it is a little reminder app that sends nicely scheduled reminders from your personal email.

The product already exists and has some 90 users. The issue is that almost half do not connect their emails, and it is not clear whether the permission page is scaring them off or they don't see any value yet.

Would you use such an app as a freelancer? What would convince you or what would drive you away? I am not looking for upvotes but honest feedback about the first two minutes of the user experience.