What free apps do you have or recommend that works for a macbook for organization of research paper?

So I am currently working on my undergraduate thesis, and I have written about 55 pages and I am using microsoft word. As someone with ADHD, I already have terrible organization skills and with microsoft word the problem is word documents, for me at least, are just difficult to organize. I am constantly moving things around in the paper, and sometimes I need to change big parts of chapters but that requires me to create seperate documents just so I can quickly go through them and see which sections need revisions. Microsoft word also doesnt have templates with chapter breaks so I have to create a new document for every chapter which compounds the time wasting and format correcting when I need to copy and paste and edit different chapters.

Also with word copying and pasting usually causes horrendeous results. I have pdf versions of all my sources so if im quoting directly from them and I paste using any one of the paste options, the pasting still causes my documents format to completely go nuts.

So what apps would you recommend for a macbook for organization especially for writing large research papers that addresses the problems I stated?

The best app ive come across so far is Scrivener, but it costs a lot for a college student like me so is there anything that is like Scrivener but free or at a discount for college students that you use or know of?