If you're a student, then chances are that 2/3 of those options won't work....
I doubt they'd let you download apps, and "going linux" would also be blocked/have consequences. The best way(or so I've found) is to use one of these two websites.
This website's amazing. It has a GREAT replica of inkscape, and is purely online. All you need is wifi. You do need a google drive account to save your files, though, and it can become a bit laggy.
The other option is:
I mostly use this- for the most part, because I didn't know about the other website. It works fine- however, you'll need to work it out by yourself(or ask me for help). The reason is that it's not like Inkscape, so you have to vary how you make maps a bit. I've worked out all problems I've had without an issue, so it should be fine!
(Here's a map I made with this website:https://www.warlight.net/Play?PreviewMap=51931
Just to show that even thought it's different than Inkscape, it still works fine!
Hope this helped you!