I assume that you have been trying to access your Export PDF subscription through wrong application Adobe Acrobat DC not Reader DC?
Please ensure that you are working with Adobe Reader DC not Acrobat DC to access Export PDF and "Signed In" using correct email.
We have checked your account and found an active subscription of Adobe Export PDF registered under it. So you should be able to access the service without any trouble.
Adobe Export PDF https://helpx.adobe.com/document-cloud/help/using-exportpdf.html is an online service that you can access online via- https://cloud.acrobat.com/exportpdf
You can also use the services through free desktop version of Adobe Reader- Adobe Acrobat Reader DC Install for all versions
You just need to “Sign In” using the email (Adobe ID) under which you have subscription registered.
For any troubleshooting, refer to- https://forums.adobe.com/docs/DOC-8841
Let us know if it still doesn't work.