We're sorry for the trouble you had while converting a PDF file, I have checked the records with your current Adobe ID which you have used to log-in on Adobe forums and found that the Adobe ExportPDF service is canceled and inactive and this is the reason you are not able to export the PDF and getting the purchase page.
You can also check your plan details on Adobe.com>Manage Account>Plans and Products or can refer to Adobe article Account and membership help
If you have subscribed with a different Adobe ID(email address), then you can use the service through the URL https://cloud.acrobat.com/exportpdf
For troubleshooting, you can refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
Feel free to update this discussion for any further assistance.