Cannot access HD partition in doing recovery

So I am currently trying to find some files for a family member business. I checked her old PC's and couldn't find them. Then I remembered she used to have a mini D-Link server. That unfortunately conked out, but I got the HDD out that she was using.

I mounted it on my external dock. Windows acknoldged that something was plugged in but I couldnt see anything. The partition I need shows up in disk manager, but I could not manually set the drive letters.

Now I decided to use my usb boot of ubuntu to see if I could access. I can mount partition 1 & 4 which are both about 500mb, but not the 500gb Partition 2 which I need

This is way out of my wheelhouse now since I don't really understand why I cannot access it, do any of you have ideas, I've included a screenshot below of the HDD info as shown on Ubuntu

https://imgur.com/tG5GHEr