Adobe Document Cloud
Adobe Reader mobile products (for iOS, Android, and Windows Phone) provide integrated support for Document Cloud.
You can create an account and store your files on Document Cloud for free.
If you paid for a Document Cloud PDF service (such as Adobe ExportPDF or Adobe PDF Pack), your files that have been converted from/to the PDF format are stored on Document Cloud as well.
Please visit the Adobe Document Cloud forum, if you have any other questions about Document Cloud.
Adobe Creative Cloud
https://assets.adobe.com/files
If you have a Creative Cloud subscription, your files are stored on the Creative Cloud storage, which is different from the Document Cloud storage.
Please visit the Adobe Creative Cloud forum, if you have any other questions about Creative Cloud.
Adobe Workspaces (retired in January 6, 2015)
End of support for Workspaces on Acrobat.com and some Adobe online services