To build your own links set in the footer, you have to go to "Link List" module settings and click "New Block" there. Write a title, select "displayAmpFooter" hook and needed links.
Go to AMP Settings → Footer, and enable "Display Social Icons". Then paste links to your social account. Empty links will not be shown at the front page
Go to AMP Settings → Footer, and enable "Display Payment Icons". Then select icons to show.
Go to AMP Settings → Footer, and change the text
You can customize the footer, add your content, remove some parts in the file
Please make sure your custom code is AMP Valid. Use this tool to validate your code https://validator.ampproject.org