More detailed instructions can be found here. You can re-enable Fast Startup after installing GRUB, and it seems not to cause any problems with Ubuntu/GRUB booting. Just make sure it's disabled during the installation.
More detailed instructions can be found here. You can re-enable Fast Startup after installing GRUB, and it seems not to cause any problems with Ubuntu/GRUB booting. Just make sure it's disabled during the installation.