Hey @garv.agarwal thanks for sharing that link - I noticed a couple of things in your project:
The first was that you were setting the Background Picture of your Screen, rather than working with the properties of the PDF component.
The background picture property can only be .png, .jpg etc.
Next was that your PDF viewer seemed to be invisible:
To resolve this make sure that the “visible” switch is set to true.
When the PDF viewer is visible in the designer you can see the prompt: “Please view the PDF file on the phone”, so web testing is not the way to go here.
Finally, when I open the app on Thunkable Live the PDF seems to load fine for me: