We apologize for the inconvenience caused, as per the description above, you are not able to access the website of Adobe PDFPack services, Is that correct?
There isn't any issue reported for the Adobe Document Cloud website, try accessing the services through the URL https://cloud.acrobat.com/combinepdf on a different browser like Chrome or Firefox or Safari.
If it is a browser specific, then try clearing the cache, cookies, temp files or reset the browser to default if possible (make sure to backup bookmarks/link/passwords saved in the browser before resetting it) and try signing in to Adobe Document Cloud website.
For more troubleshooting, you may refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
Let us know how it goes and share your findings.