How to use shinyShortcut package on linux

I am trying to create an shiny app for people that are not R users (they even may be frightened :D). After the question about server/local app here (How to import remote csv file on a deployed shiny app?), I try to use the shinyShortcut package solution.

I did the following:

devtools::install_github("ewan-keith/shinyShortcut")
library(shinyShortcut)

shinyShortcut(shinyDirectory = "/home/cha/Server",
              OS = "unix")

then I got :

So I have all that is normally required (at least that is what I think).

Since I never used the .desktop before, I ran the instruction here.

1. I put the .desktop on my desktop
2. Right click and change setting the tutorial did
3. I allow again from a right click and the .desktop disappears. Everything seemed ok.

However, when I double-clicked on the icon, nothing happened... I tried to change the web browser or the application to launch it, nothing works.

What did I misunderstand ?

Thanks in advance

Charlotte (Ubuntu 20.04)