BRGHT, Thanks for posting this question. Typically,
Just to highlight, typically the "Invalid WNS credentials" error message indicates that the Package SID or Security Key you are using to configure WNS for your notification hub is incorrect.
Please double-check that you have entered the correct values for the Package SID and Security Key in the Azure portal.
You may find these values in the Windows Dev Center dashboard for your app.
Just to isolate, kindly ensure that you have selected the correct package type
when you created your Package SID in the Windows Dev Center dashboard.
Also, see checkout Push notification service request and response headers to ensure that your app server is using all custom headers as described.
Notification request returns "400 Bad Request"
Kindly let us know how it goes, I'll follow-up with you .