Follow the instuction

https://docs.microsoft.com/en-us/power-bi/developer/embed-sample-for-customers

use Embedding setup tool to download the sample code, run below error all the time.

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 343:                // Authentication using master user credentials
Line 344:                var credential = new UserPasswordCredential(Username, Password);
Line 345:                authenticationResult = await authenticationContext.AcquireTokenAsync(ResourceUrl, ApplicationId, credential).ConfigureAwait(false);Line 346:
Line 347:            }

Source File: C:\PowerBI-Developer-Samples\App Owns Data\PowerBIEmbedded_AppOwnsData\Services\EmbedService.cs    Line: 345