PowerBi Gateway can't use Custom Connector because directory isn't accessable for service account

[Benny-Sam]

The configuration tool write out the error, that the service account can't access the directory for the custom connector. I used my domain account and an local account, both are member of the administrators. I used the default account an grant access to the folder with the connectors and created the default path and grant access for the deafult account. The Gateway is configured in the PowerBi cloud

But every time the configuration tool writes down the error and i can't choose an custom connector. I start the test in June 2021 und the last update was downloaded and installed today (2021-08-30) on an Win 10 Enterprise.

What can i do? Where can i get informations to analyse this error?