Hi Colin,
Sorry to hear about your poor experience. We see that you have an active subscription registered under your account. Since its a web based service, so you can start using it on new computer as well.
Make sure that you have the correct application Adobe Reader DC installed. If you have Acrobat DC installed, then you need to uninstall it first to avoid any confusion.
Follow the steps mentioned below, to activate the subscription.
1- Export PDF is an online service that you can use online via: Adobe Document Cloud
2- You can also use the services through free desktop version of Adobe Acrobat Reader DC: Adobe Acrobat Reader DC Install for all versions
3- “Sign In” using the email (Adobe ID) under which you have subscription registered.
4- For detailed description of how to use the Export PDF service, you may refer to- Using Adobe Export PDF
You may refer to the following link for any troubleshooting: Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud Services).
Let us know if it still doesn't work.
Regards,
Akanchha