Html – How do I block access to a file directory in htaccess

I’m working on a website of some sorts with folders to store all the files.
The url is like this:

example.glitch.me/examplefolder/example.html

yup, i’m using glitch to build the website, i can’t afford custom domains

Anyways, if I do this:

example.glitch.me/examplefolder

Here’s what the file directory looks like:
file directory

I see all of the files inside this folder, and I want to prevent this in some way, I’ve tried the .htaccess Options All -Indexes or the Options -Indexes but it doesn’t work for me, I need your help!