Can't install version downloaded today

This is the error I got.

JFolder::create: Could not create directory
Warning! Failed to move file.

This has nothing to do with the MobileJoomla component.
Did you check Help - System Information - Folder rights to see if all necessary folders are writable?

MobileJoomla requires the following folders be writable:
/administrator/components
/components
/modules
/plugins
/plugins/system
/templates