The Payment Page can be enabled by adjusting the TeamRaiser event settings:
  1. Edit the Teamraiser.
  2. Go to Step 3 Select event options.
  3. Under the Related Actions below the main menu list, click Edit Advanced Options -> Step A: Define Fundraising Options -> Step 22: Donations 2 Registration Transaction Processing.
  4. Mark the checkbox for Yes, enable Donations 2 processing for registration transactions.
This enables the "Payment Page" in the Customize Pages list. It will replace the billing page during the registration process.