Hi khoa,
Target actually have 2 versions: one is Test & Target (we called Target Classic), the other is Target Standard. You are able to access Target with your Adobe ID, that is to the Target Standard; In your AEM integration experiment, that is to Target Classic which don’t support Adobe ID authentication. In order to make your AEM integration success, You need to provide Adobe Target Classic email address and password.
To access Adobe target Classic , you need to have Target classic credentials which can be created raising a client care request.
If you are a supported user for your company account you can contact Customer Care. To contact Customer Care by telephone, call 1-800-497-0335. Toll free numbers outside the United States can be found on the Adobe Digital Marketing Customer Care Regional Phone Numbers page (https://helpx.adobe.com/contact/dma-external/DMACustomeCareRegionalPhoneNumbers.html). When asked to select an option for your product, press 3 to contact the Target team.
E-mail Customer Care at tt-support@adobe.com.
Please Note: If you are not a supported user for your account please reach out to account manager for your account.
Thanks & Regards
Parit Mittal