An error occurred (InvalidParameterValueException) when calling the UpdateDashboardPermissions operation: Principal ARN “firstname.lastname” is not part of the same account ############
As you are looking at admin capabilities, getting familiar with the QuickSight API’s would make it easier . This would also give you an understanding of the structure of an ARN . My recommendation is look into the following workshop and it’s modules : Workshop Studio
As for your question , you will find an example here : Workshop Studio ( exercise 7 )