Create an app in https://developers.facebook.com/apps/
Choose other
Choose type as business
Name the app and click create
Add products marketing api and facebook login for business
Go to Settings → Basic and retrieve the appid and secret
Go to Tools → Graph api explorer
Select your app and add the permissions needed. Click Generate token
Copy the token and create a Long lived Access Token Get Long-Lived Tokens - Facebook Login - Documentation - Meta for Developers