Sorry to hear the inconvenience caused.
Could you please confirm, how exactly you have been trying to convert the pdf file to word?
If you are converting the file using web browser through- https://cloud.acrobat.com/ then you may try a different web browser.
Check with a different file and see if that helps. Also there is a limitation for the file size to be uploaded for conversion-
For further troubleshooting you may refer to-Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
Let us know if it still doesn't work.