Error message when trying to connect to server

[Sister Sabina]

I'm getting the following message when trying to sync my CC files across machines.  The msg refers to syncing libraies.  Does anybody have a solution as to what may be causing this and how to resolve it please?

Thanking you,

Sister Sabina

[Sister Sabina]

I should have added that I'm using Catalina on one of my MacBook Pros and macOSHigh Sierra on another.  Then I also have a Windows Surface Pro 7 with CC installed.