How to add Image at the center bottom of each page of existing pdf

Hi,Support:

Is there any way to work it out for adding a same mage with autosize to pagesize and rotation30 to the center bottom of each page of existing pdf?
I tried a demo like https://docs.aspose.com/pdf/net/working-with-images/, but there is no image to be sucesssfully added in the output.pdf based on Pdf.dll v20.7 and Net2008/Net3.5.
Would you please show me a right one?

Thanks for your help!

@ducaisoft

You can achieve it by adding image stamp inside PDF document. However, please share your sample input image and an expected output PDF document if you notice any issue while achieving it.