The payment method for PayPal transactions is identified as 'XCheckout' in a Transaction Details report. Here is how you can configure this type of report to show these transactions.
  1. Navigate to Data Management > Reports
  2. Click 'Create a New Report'
  3. Click on the Select Application menu; select Transactions
  4. Select Transaction Details; click Next
  5. Select the desired columns (recommended: Contact ID, First Name, Last Name, Payment Method, and Transaction Date); click Next
  6. Arrange the columns in whichever order desired; click Next
  7. Choose how the report will be sorted; click Next
  8. The report should have following two filters; though, you can add more should you desire:
    1. To find all approved transactions: Transaction Purpose = Credit, Debit
    2. To find PayPal transactions: Payment Method = XCheckout
  9. Follow the remaining steps to save and run your report. Only donations PayPal will be returned in the results.
To add these donors to a group, see Add Constituents from Report Results to a Group