Level 3 Advanced Training UiDemo - InitAllApplications error

Hello everyone. I am new in Uipath and I am following Uipath academy video tutorials and I am stuck at UiDemo exercise. Following the pdf steps, I execute InitAllApplication.xaml and UiDemo app opens followed by this error :
" 19.7.0+Branch.master.Sha.8c253d13718eed5c7db27daef6facd1fe1b0d067

Source: Invoke Workflow File

Message: Object reference not set to an instance of an object.

Exception Type: System.NullReferenceException

RemoteException wrapping System.NullReferenceException: Object reference not set to an instance of an object.
at UiPath.Core.Activities.ScopeActivity.OnFaulted(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
at System.Activities.Runtime.FaultCallbackWrapper.Invoke(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
at System.Activities.Runtime.FaultCallbackWrapper.FaultWorkItem.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)
"

I have also another question. At this point Username and Password fields will be filled automatically or this happens in another moment?
I hope anyone will help me to pass this problem :slightly_smiling_face::slightly_smiling_face:

Thank you.

@Amario

Welcome to the uipath community.

If you are using Orchestrator then credentials should be saved in Orchestrator Assets and read from it else it should be saved in windows credential manager.

Run the workflow in debug mode and check where is the problem.