Any OS needs a bootloader, even Windows(i.e. ntldr). Linux isn't too picky about which bootloader you use, but definitely has to have one, and grub is the standard choice these days because it's so flexible.

I wouldn't expect a Windows disk manager to have any idea what a Linux system partition looks like. There's whole categories of information it's not telling you. 'fdisk -l' in a linux shell would be much more useful than a windows screenshot.