If a disconnect has occurred between ManyChat and InstantPage.dev , please check the followings.
Visit ManyChat portal, go to "settings" -> "Extensions" -> "Apps" ,and click "InstantPage"
Check the setting is correct or not.
"Enter Your Website Url:" = your InstantPage.dev main website URL, you can copy it from your InstantPage portal. Login to your InstantPage dashboard -> "Domain"->
Select "System Domain" if you don't have custom domain , copy the system domain without www -> copy portal.instantpage.dev
Select "Custom domain if you have your custom domain linked with us. Copy your custom domain, instead of portal.instantpage.dev.
Visit the ManyChat portal again and put the correct website URL.
Adding your API key
To ensure security and account verification your website's API Key is also required.
To find your API Key > Settings > Applications > reveal API Key
Visit the ManyChat portal again and put the correct website API.
Refresh the page and test your flow.
Start with ManyChat x InstantPage.dev Official Integrated App