We apologize for the inconvenience caused, as per the description above, you are not able to convert a PDF file into Word, Is that correct?
Please try exporting the PDF using the URL https://cloud.acrobat.com/exportpdf with your Adobe ID and password on a different browser like Chrome, or Firefox, or Safari and see if this brings any difference.
If you are using the free desktop version of Adobe Reader DC and facing the issue, please sign out and sign back in with your Adobe ID and password in Adobe Reader and then try exporting the PDF file.
For more troubleshooting, refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
More about ExportPDF: FAQ | Adobe Export PDF, Document Cloud
Let us know how it goes.