There could be a few reasons why you're unable to download the .ics file when using Chrome or Firefox. Here are a few potential solutions:
-Make sure that you are using the latest version of your browser. If you're not, try updating and see if that solves the problem.
-Try clearing your browser's cache and cookies. This can sometimes solve issues with loading or displaying files.
-If you're still having trouble, try using a different browser. Sometimes one browser will work when another doesn't.