Global scale is not offered for docker deployment on two servers, but rather is used at the enterprise level for many millions of users.
Global scale is not intended for personal docker deployment, and unfortunately the process of having two mirrored Nextcloud servers is not clear in existing documentation.
It is currently outside the knowledge base. See other threads on the forum discussing mirrored Nextcloud across two or more servers, which is a different conversation from Global Scale; understandable on confusing them. 
Closing this thread since it relates to Global Scale and was answered @Ron_Nahmany but we can continue the mirror discussion on the mirror thread. I would love to figure that out.