Hello,
1) You can ignore the mentioned message. Our theme uses Header Builder that allows placing menus in any part of the header http://prntscr.com/rvfh9t , so there are no Manage Menu Locations settings.
2) Download admin.php and walker.php files by this link – https://dropmefiles.com/Vy6LP , reupload these files in xstore/framework/thirdparty/menu-images/inc folder via FTP.
Regards