Unable to update CoursesPress Pro

I tried 3 times to update the plugin for version

1) from the WPMU Dashboard - i just get error "unnown error" in a red Notification bar
2) via the link in the list of plugins in the admin site - i just get error "unnown error"

3) via checkbox and batch operation (to see the process page of plugin update)
And just there i get a error message, that could help:


Cannot copy file: coursepress/includes/external/tcpdf/fonts/dejavusansmonob.z

Seems this file is missing somehow in the download? At least - it breaks the update process.

Please advise what to do...