Thank you for contacting Syncfusion support.
We have analyzed the provided sample and found that you have not provided the serviceUrl for the PDF Viewer. Our PDF Viewer control is both server and the client side oriented. PDF viewer control processes the PDF document in the server side and send the processed PDF data to the client using the web service to render the PDF document and for further operations in PDF viewer. So, we need to provide the serviceUrl to the render the PDF document in PDF Viewer.
We have shared the simple PDF Viewer sample in the following location,
Kindly run the web service project first and provide that URL to the serviceUrl property of the PDF Viewer.
Note: We are facing some issue in connecting our online web service, we will resolve the issue and refresh it as soon as possible.
Please find the below link to create web service project,
Please try this and let us know if you have any concerns on this.