MDL Marching Percussion Download

I've been using musecore for quite some time now and have run into an issue. I cannot download the MDL Marching Percussion stuff. I have it successfully downloaded onto my other computer but cannot get it on this one. It say go to the help bar then to "Resource Manager" but Resource Manager Simply doesn't exsits on Musescore for mac (or at least mine). What should I do?

Thanks!