you never said anything about PDF powerpoint or jpg anywhere in your problem description, you said
“The reason why is the PC was used to control a meeting menu that changed 3 times a day,” the closest thing i could translate meeting menu to is a calendar.
that said, if you want to have a powerpoint, a PDF, or a JPG, or any mixture of the same playing in a Xibo layout, you just add the content to the layout and then either have the administrative person REPLACE the media in the content library whenever it changes, or build dynamic playlists that will update the media in the layout whenever new media is uploaded that meets the proper criteria. all they have to do is log in to the web portal and upload the content when it needs to be changed and xibo does the rest.
it’s literally what the system is for.
you don’t have to redesign your layout every single time you want to update the content. if that was the case, literally no one would use the software