I am running in to an issue where i am not able to share files with my co-workers via the cloud. They receive the email invite, but when they try to open it they get an error message saying "Sorry we can't open this document. You don't have permission to open this document. Contact the owner for access or check to see if you are logged in with the right account." I have checked on updates for both sides and everything has been fully updated. This issue has come up a few times now, and any pointers on how to resolve would be aweosme!
I had this problem couple times and the cause was e-mail aliases. Infrastructure team from my company put some aliases in our emails and we never know for certain what is domain and what is an alias. We were able to receive e-mails about shared documents bit the e-mail wasn't matching the e-mail from out adobe account. I'd suggest to take a look at this.
Sorry to hear about the trouble. In addition to the suggestions shared by FrancoBits, please try inviting a different user and user with different domain. Let us know how it goes, we'll try our best to help you with it.