I think you'll need a couple of things to get this working.
1. You need to install Qt Data Visualization library (version 5 or above). The Qt Installer can be used for this.
2. You'll need to rebuild Kstars and the build process needs to know you have the Qt Data Visualization library installed. Some platforms have this on by default and some don't. So the make files need to have this switched on. On my setup there are switches for HAVE_DATAVISUALIZATION that need to be enabled.

I think it was done this way when the utility was first built because the Qt Data Visualization wasn't available on all platforms. I don't think this is the case anymore but the build scripts may not all have kept pace with the platform changes.

HTH

Ok seems like ppa builds doesn'ŧ have that enabled. First uninstall all indi and kstars packages from PPA. Then you can use my scripts to compile and install whole INDI and KStars which should have data visualization enabled. You can find them here.

gitea.nouspiro.space/nou/astro-soft-build.git/

They should work on any Debian based distro like Ubuntu or Mate. Clone repository then run install-dependencies.sh (just first time) and then build-soft-stable.sh

Following these replies do you think to implement the maximum digital number visualization with median value?
Furthermore, please, take in account the developement of tool as for the flat time exp time evaluation, the exposure time setting or computation based on a star max value. I mean, the user select the star and the related its max value and ekos computes the exposure time satisfying this max.
Thank you for your great job.