Win11 installation & access from Mac desktop

Hi all,
I'm running Win7 and recently I keep getting a pop-up window asking me to upgrade to Win11. When I proceeded, I got an error message saying I need to free up some space in that particular directory (please see attached screenshots: http://u.pc.cd/Eyw7). But when I used a terminal to access that directory, it's all empty.

Now I'm a bit lost and asking for help regarding the following two issues:
1) Win7 is probably too old and I'm happy to upgrade to Win11 for free. But how can I actually do it? As mentioned above, it asked me to free up space but there's no files/sub-directories in that directory

2) How can I access the Windows partition from my Mac desktop? If I could do this, it *might* make things easier cos I could just back up all the important files, format that Windows partition and then do a fresh installation of Win11, followed by installation of Parallels Desktop.

Any help would be much appreciated!