Hello Tsuriki,
The user owning the email address shared has admin access to three accounts. If you logged in with the credentials of this email id, you will be able to see the list of all accounts which are directly accessible to this email id. To create the campaign under your account via API, you will need to set the client customer id of your account in the request header. Or you can set the client customer id in the property file. Please refer to sample property file
here. Also, refer to sample Java
code to create the campaign. Samples in other languages can be found
here.
To link the youtube, please refer to
this Help Center article. Let me know if you have any further questions.
Thanks,
Milind, AdWords API Team