So, please understand that a ChromeBook runs Android - a version of Linux for Phones.
The Apps you install on ChromeBook are either Apps for Android or Apps for Linux.
Unlike Apple, there ARE torrent apps for Android (BigyBT is often listed as a favorite for Android, but I don't use Android Apps so I have no personal knowledge... and qBitTorrent is available for Linux, and I personally use qBitTorrent on Linux and it's great - though it does look/feel more like a Windows App even on Linux.. but that's the point: Same interface, all platforms!)
I don't know how seeding will work in this environment, but it'd be cool if you wrote back here if/when you figured it all out! 🙂