Step 1
Go to developers.facebook.com
Log in with the admin account of your ad account
Step 2
Click "My Apps"
Step 3
Create an app
Use case -> Other
Type -> Company
Add app name, then create app (there is no need to select a business)
Step 4
Set up the Marketing API product
Go to tools, select all and press Get token
Step 5
Copy the access token
Paste the token in the adset configurator of the extension