Sign-in. The apps at ppipl.app use Google sign-in only to learn your e-mail address and check it against the list of people invited to each app. We do not receive your Google password, contacts, files or any other Google data.
What is kept. A sign-in cookie on your device (up to 7 days), and the web server's routine logs (time, address, page), kept for a limited time for security and to fix problems. Nothing is sold or shared, and there is no advertising or tracking.
Questions. Ask the person who invited you, or write to the ppipl.app team.