Sorry for the delay in response to your query.
As per the description above, you are not able to convert PDF file into Excel as getting error message Conversion Failed, Is that correct?
Please check the PDF file's security settings from Document Properties.
> Open the PDF> Click on File>Select Properties>Select Security tab.
If the PDF file is set for encryption the file cannot be exported.
You can also go through the link for more information: https://helpx.adobe.com/acrobat-com/kb/file-never-converts.html
How to convert PDF to Excel: https://acrobat.adobe.com/in/en/acrobat/how-to/pdf-to-excel-xlsx-converter.html
Keep us posted with the results.