1. First, select the Fastcard you are using for your campaign and click on edit.
2. Now click in "Integrations" on the left side panel of options and then on "+Add integration"
3. Select the Facebook account where your campaign is.
4. Select the campaign where you are going to be using the Fastcard
5. Select the Ad set, and the Ad where you are going to be using the Fastcard
6. Copy the URL and paste it into the website URL field when setting your creative on the Facebook Ads Manager.
7. After pasting and publishing your campaign click on "Verify" and then "done"
8. After completing the whole process you should be able to see your integration verified under the "integrations" section to the left of the website.