Hi Joser,
As per the issue description mentioned above, you are facing issue when trying to combine files, is that correct?
As we have checked the account details using the email address you are logged into the forums, you have subscription for PDF Pack.
Please refer to the following forum threads discussing the similar issue:
Page Extraction is showing as Not Allowed in Adobe Reader XI
How to allow "Page Extraction"?
You may also refer to: Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud Services).
Let us know if you need any help.
Shivam