I'm getting this message, however my Muse is up-to-date and I just downloaded Mavericks.
"This Adobe muse site file requires a newer version of Adobe Muse. Please update to a newer version"
It seems to work fine on my iMac but when it's on the macbook it won't open.
A chat session where an agent may remotely look inside your computer may help
Creative Cloud chat support (all Creative Cloud customer service issues)