d/l the tar.gz file and extract it. Click VentoyGUI.x86_64.
Took me a while to figure this out. LOL.
It's especially useful if you want to install Tiny11 since Balena Etcher can't do Windows iso's. Neither can Unetbootin. BTW, Unetbootin is great for creating a FreeDOS boot thumb-drive for updating your BIOS.
My way seems easier.
Odd. Single click on VentoyGUI.x86_64: nothing happens. Double-click: nothing happens. Right-click and "open": nothing happens.
But the web method does work for me.
Try to right click on the file and go into properties to check the permissions. I don't remember the exact wording but should be something that makes the file "executable". Alternatively, from the command line:
chmod u+x VentoyGUI.x86_64
And try again. You can also try to run it from the terminal like so:
./VentoyGUI.x86_64
You may also need to specify the full path to this file, maybe it looks something like
/home/4box/Downloads/VentoyGUI.x86_64.
If there's something wrong when you run it from the terminal you will most likely see some kind of message that can hopefully lead to the cause of the issue.
In Permissions:
And I can't do the command line because I'm too incompetent with it to get any result other than "no such file or directory" (I'm not sure how I did it before, I'd have to find the online instructions again). Whatever I type after "cd" ain't working.
How did you installed / downloaded it, and which version?
I can't remember how. I followed instructions in an online tutorial (which explained the web server route) but I can't find it again. (Not history, not bookmarks, not re-googling.)
Not a big deal: I've already got Ventoy installed and working on a USB so I'm OK for now.
Version: 1.0.91
A while back I installed Nemo as the principal file manager, whereas ZL's default is Thunar.
Today I redownloaded Ventoy, extracted and clicked on VentoyGUI.x86_x64... and again no reaction. At least, no reaction when clicking in Nemo.
So then I tried clicking in Thunar, and up popped the window asking me for my root password and once entered, the Ventoy GUI appeared. 
So I guess now I have to find out what's the problem with Nemo.
I guess it's just not configured to allow executables to run by default? I don't know I haven't really use it in that way.
However I found this thread over on the Linux Mint forums, maybe this suggestion helps:
https://forums.linuxmint.com/viewtopic.php?p=2338477&sid=f7d97cdbe2ad2b9cc415f04910b7c4dd#p2338477
Thanks.
if you have trouble using ventoy use :
sudo bash VentoyWeb.sh
