If you are get credentials from the windows credential manager, using the Get Credential activity will not work because that activity is used to get credentials from the orchestrator.
For you to get credentials from the windows credential manager, you have to use the Get Secure Credential activity.
Check the attached workflow for a sample. Here it tries to get credential from the orchestrator. If not available it tries to get credentials from the Windows credential store. So first it tries to get it, if its not available, it requests the credentials from us and stores it there. Next time when it runs, it directly gets the credentials from there.
So in the attached workflow, check the Catch section for the windows credential
GetAppCredentials.xaml (13.3 KB)