Now, I was going about my data science stuff and downloaded a 12GB file, and un-zipped it. I start getting errors saying that I do not have enough memory. I know I have ~1TB allocated to Linux.
All I can tell is that I was working in /Home/myusername assuming that that's where most of my space was allocated, but it seems as though ~800GB are in /HOME. Since I'm new to Linux I'm a little confused. Any ideas on how to go about this? Should I just start using /HOME or is there a proper way to reallocate space?
The default Linux file system is case sensitive. You have defined a mountpoint at /HOME when instead, you should have used /home. Therefore, the /HOME is simply not used, it is not your actual home directory, that is in /home/username which is completely separate from /HOME.
To fix this and use the 874G partition you have created as your actual home directory (in the Linux world, your home dir is referred to as $HOME (note the $) or ~/), you will need to follow these steps:
df -hand check the free space.