New Overleaf users will receive an email with the subject "Confirmation instructions" prompting them to click a link in order to confirm their email address. We recommend you check your spam folder(s) for this email if it hasn't appeared in your inbox a few minutes after you've signed up.
If you've checked your spam folder and still don't see an email from us, on the sign-in page there's a link labelled "Didn't receive confirmation instructions?". Clicking this link will allow you to re-send the confirmation email to your email address.
Please do get in touch if you need any additional assistance - we're happy to help, and you can reach us via our contact page.