Quicksight - Migrating dashboards between accounts issue

Question

I am trying to create a mechanism for copying dashboards from one environment to another because we have several dozen clients who will need to update multiple dashboards. Therefore, the process must be automated. I tried to follow the manual provided here: https://aws.amazon.com/ru/blogs/big-data/migrate-amazon-quicksight-across-aws-accounts/, but the last step - creating a dashboard in the target account using the ARN template from the source account - is not working for me. I have created a role granting all necessary permissions on QuickSight in the source account for users from the target account (for testing purposes, I even gave administrator rights to any user from the target account). However, I still get an "Access Denied" error. What could be the problem? As far as I understand, this should work without assuming a role (for security reasons, we prefer not to use this option), but maybe I am mistaken. Thank you in advance.