The only requirement is that a user common across all the nodes in the cluster be identified as the MapR Administrator user. That user is the logical "super user" of the cluster (in the same way that "oracle" is often the super-user of Oracle Database installations, if you're familiar with that product).
Most MapR deployments will use the default "mapr" user account as that administrative user. But, as Nabeel points out, that is not a requirement. You can specify any user you like. The configure.sh command executed during cluster setup will create the admin user if it does not already exist
NOTE; performing a manual installation and allowing configure.sh to create a new user can be problematic ...
since the different nodes in the cluster may wind up with different user id's for the same name.
It is considered a best practice to create the user yourself (consistently across all nodes) or let the
MapR installer perform the complete installation. The installer will generate an error if there is a
mismatch of user id's for the administrative user between the different nodes on the cluster.
Retrieving data ...