Are you using our PayPal buttons but orders aren't showing up in your account? Depending on your PayPal account type and settings, you may need to make a few changes.
1) Make sure you are "capturing" the funds, not just "authorizing". By default FetchApp doesn't import the order until it has been marked as "Paid".
2) Make sure IPN is enabled. For most PayPal accounts this setting is found here: https://www.paypal.com/us/cgi-bin/webscr?cmd=_profile-ipn-notify. If it asks for a Notification URL, you can use https://YOURACCOUNT.fetchapp.com/paypal (replace YOURACCOUNT with your actual FetchApp account).
3) You can view / resend failed IPNs by going to https://www.paypal.com/us/cgi-bin/webscr?cmd=_display-ipns-history