In the pushly-amp-helper-frame.html and pushly-amp-permission-dialog.html files replace the REPLACE_WITH_DOMAIN_KEY placeholder text with the Domain Key from the platform.
Place all 3 files in a publicly accessible directory on the domain for which you are going to opt-in visitors.
Step 2: Include the AMP Project Javascript
Include the following script tag on your AMP pages in the HTML head section. Ensure that the AMP page does not include the main Pushly SDK snippet.