403-Forbidden response after successful login

[bennosteineggersys]

I cloned this repo & installed all the required tools. Afterwards I build the project without any problems. I have chosen option 1 to export all customers. After logging in in my browser, the website said something like: successfull login, you can close the tab. But a System.Net.Http.HttpRequestException: 'Response status code does not indicate success: 403 (Forbidden).' was thrown. The (sandbox-) account I am using has all the peremissions needed for this action.

I am using Visual Studio 2022 and .NET 6

The detailed error message is:
System.Net.Http.HttpRequestException HResult=0x80131500 Message=Response status code does not indicate success: 403 (Forbidden). Source=System.Net.Http StackTrace: at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode() at NCEBulkMigrationTool.CustomerProvider.<ExportCustomersAsync>d__2.MoveNext() in C:\Users\bst\Documents\projects\Partner-Center-Tool\NCEBulkMigrationTool\CustomerProvider.cs:line 81 at Program.<<<Main>$>g__RunAsync|0_1>d.MoveNext() in C:\Users\bst\Documents\projects\Partner-Center-Tool\NCEBulkMigrationTool\Program.cs:line 98 at Program.<<Main>$>d__0.MoveNext() in C:\Users\bst\Documents\projects\Partner-Center-Tool\NCEBulkMigrationTool\Program.cs:line 60