Hi @Etomasetti! Welcome!
It looks like you found some of the info you'll need to fix the problem! 
The message in your screenshot indicates that on line 8 of your ui.R file you are referencing a file path that leads outside of your project directory. You might want to take a look at this section of the shinyapps.io user guide to understand why that's a problem: http://docs.rstudio.com/shinyapps.io/Storage.html
So the simple answer is that you need to change the file path (and probably the location of the file!) that you're accessing on line 8 of ui.R so that it is a relative path to somewhere inside your project directory. If it's not obvious how to make that work in your context, then I think you'll need to supply more information, such as:
- The code for
ui.R - What constraints of your situation led you to refer to a file from somewhere outside your project directory, and what the challenges are to meeting the requirements outlined in the link above.
You might also want to read these references for advice on shiny debugging and how to find your application's logs:
- http://docs.rstudio.com/shinyapps.io/applications.html#debugging-your-application
- https://shiny.rstudio.com/articles/debugging.html
- Our Shiny debugging and reprex guide also has some good notes about the best way to ask shiny code questions here