The section 3.2.3. Step 4: Test your billing workflow contains not accurate information for 2.2 release.:

Quote:

For accounts created before 11th May 2016 you must add the snippet above manually. After said date this will be included in the template by default.

Code snippet is not also innacurate.
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Screenshot:

Next issue is with sub-chapters They are kind of weird numbered:

• 3.2. Step 1: Find the information in your Adyen account
• 3.2.1. Step 2: Configure your payment gateway in your 3scale account
• 3.2.2. Step 3: Enable the "alias" additional data in the Adyen API response
  ...