After 2021 Update, cannot open company

SUGGESTED

We updated Sage 50 to the 2021.0.0 version, and since cannot open the company file (on cloud).

Message is:  "Could not sync the Remote Data Access company.  Please try again.  If the issues continue, download the company again."

I have tried all of these, plus trying to restore from backup.  I cannot do any of it.

My computer is the "server."  My boss accesses it remotely.  

PLEASE help.  I have payroll and billing I can't do!