Two problems:
-
Improper configuration
You need to configure your repository to install the packages needed for Voila. They aren’t there by default. See the first paragraph in my reply here.
-
The URL
In the ‘URL to open’ space on the form, you don’t want a slash on the left side of
voila
.
I cannot see the rest from your image. Always best to include text, even to accompany an image, so others can edit and try.