I have here a VERY simple three letter word generator, however on .exe and Apk build it works fine but when i put it on Itch.io it doesn't show the letters generating.

I built it in Unity if that makes any difference. 

https://making-english-fun.itch.io/cvc-word-maker

Any advice would be great as it is made  for my kids at school ( i am a teacher) the developer i asked for help seems to have lost interest and jsut says somethign about cheap server and multi threading.

You may want to take a look at the browser console to see if there are any messages that point you in the right direction. Errors like this aren’t specific to itch.io, but typically related to the HTML5 export you made.