Hello
I have same problem but solved by myself.
first step – change file names to:
advanced-access-manager-fr_FR.mo
advanced-access-manager-fr_FR.po
second step – edit aam.php file, change line load_plugin_textdomain to this:
load_plugin_textdomain(AAM_KEY, false, dirname(plugin_basename(__FILE__)).’/Lang/’);
Good Luck