Try this offline install
Extract contents to freshly formatted SD card
Insert SD card in Wii and power on
MMM loads via CB2
Choose Wad Manager
Choose to install all wads (press 1)
Make sure everything installs successfully
Install Priiloader prior to exiting MMM
Choose App Manager -> Priiloader and the installer will start.
Follow Instructions to install Priiloader and then exit to SM.
make a backup of your NAND with Bootmii - Not a suggestion this is mandatory so do it before doing anything else.