Hi Stefano, welcome to the forum.
You can add assembly references to your .xaml-files manually as described in this example for the DataSetExtensions reference: AsEnumerable is not a member of 'System.Data.Datatable' - #2 by loginerror
I don’t exactly know which reference you need though.
You can also try automating your PowerPoint presentation with UiPath activities. Check out PowerPoint packages and components from Go!
Cheers, Lukas