Get users with different roles and call function on each of them (user_meta)

Question

First, always var_dump() something if you aren’t sure what exactly you got. If you ain’t got XDebug installed and configured, just use

printf( '<pre>%s</pre>', htmlspecialchars( var_export( $dumpMe, true ) ) );

which will bring up an equally informative response.

About the WP_User_Query) IIRC it returns objects which are instances of WP_User. You can test that with

$user instanceof WP_User AND print 'Yes, I am a WP_User object';

If that is the case, simply use

var_dump( get_user_meta( $user->user_id ) );

and you should be fine. Btw, there’s no real Author Meta.