Hi @nadia_maciulis ,You need to provide the AEM Author instance url
while creating an external account in ACC. The same is mentioned under
Step 3 of To configure an external AEM account (section) on the
following
link:https://experienceleague.adobe.com/docs/experience-manager-65/administering/integration/campaignonpremise.html?lang=en#verifying-the-aemresourcetypefilter-option
Regards,Dhanesh