1. org-mode is already installed in Emacs. Open a .org file in Emacs and you have everything you need ready and waiting.
2. You can make an outline by putting * for first-level heading, two * for second-level, and so on.
3. You can add notes below a heading simply by typing.
4. You can link wiki-style to other documents with the shortcut C-c C-l and entering the filename. Remember to include the path as in ./filename.org. The same shortcut works to edit the link. You can click on the link to open it and then start typing.
5. You can move headings and the full subtree below them using the Alt key plus arrows. This outlining capability is very nice if you're used to it from Workflowy or Dynalist.
There are lots of other things you can do with org-mode, but as a basic way to organize your information, it's very simple even if you've never used Emacs.
Be dismissive of my comment if you want, but I'm guessing you either didn't bother to read it or to understand it, because there's nothing in there that the vast majority of computer users don't already do.