Once you have entered the Facebook business manager account; navigate to the ‘Event Manager’ page. You will see an interface like this. You need to click on ‘Data sources’. Pick the data source for which you need to integrate FB CAPI.
Now go to settings & explore the ‘Conversion API’ section. You will find an option of ‘Generate access token’. By clicking on it, you will get the access token. You need to copy and save that token safely as it won’t be stored by Facebook.
As shown in the below screenshot, go to the pixel settings in the Conversios plugin. Paste the token you have copied in Meta (Facebook) Conversion API token section.