If the file itself is larger than the discord sharing limit, it might not send. Have you tested the link on another device and did it work? In my experience I've always published my Twines as an html file and then shared it. You could also just create a new Itch project and attach the Twine as a zipped html file (setting it to running in browser or as a downloadable file) and then restrict the visibility and access to an Itch link.