Hi Marco. The Partner Name is the unique account name that is assigned when your account is created. It is also sometimes referred to as your Audience Manager subdomain, as it is going to be the subdomain associated with any of the AAM "demdex" server calls that are made when the code has been implemented.
As was mentioned by snehaa30982388 our Customer Care teams can help confirm it for you. Since an email has already been submitted, you should hear back from us shortly!