Hello duaner77620050
We apologize for the inconvenience caused, as per the description above, you are not able to combine PDF files as getting a message "Page extraction not allowed in the source PDF documents", Is that correct?
Using the Adobe PDFPack subscription, you can combine PDF files online using the URL https://cloud.acrobat.com/convertpdf with your Adobe ID and password. You can also use the free desktop version of Adobe Reader DC to use the services of Adobe PDFPack, just "sign-in" with your current Adobe ID and password in Adobe Reader.
For the error, you are getting, please refer to the following KB docs which discuss the similar issue How to allow "Page Extraction"?
Page Extraction is showing as Not Allowed in Adobe Reader XI
You may also refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud Services).
Let us know how it goes.
Regards,
Anand Sri.