If you are looking to implement Adobe Target through DTM or thinking of getting enabled on your Adobe Target Classic account, you need to know the client code of your account. In order to find the Client Code of your account you need to go to Setup > Implementation > Edit Mbox.js Settings. The Client code at the top on the settings. Please go through the below doc to know more.
This is very hard to find - (a search in help docs does not return this document) Thank you for the help though - maybe add a thesaurus entry for "client code" in the help docs