I created a user and add it in the group of administrator.
Now I create a package using package manager and include the path: /home/users/[name of user].
build the package and download it.
Install this in another AEM instance.
What i observed that user is imported but It is not assigned to administrator group.
Check this:- https://adobe-consulting-services.github.io/acs-aem-commons/features/acl-packager.html
I used it in the past in projects to set ACL permissions and users/groups between AEM instances.
Some more reference articles :-
// Copy Users, Groups, Permissions (ACLs) between Adobe CQ Instances
//Migrate Users and Groups With ACL Permissions in AEM
I hop this helps.