I recommend installing the Debian package you can download at our website since they are more up to date and contain many bug fixes, especially regarding the server/service on Linux. Our official packages contain all components so you don't need individual packages. If you want to stick with the Debian packages, installing veyon-service is sufficient. You might need veyon-configurator if you want to configure the Veyon installation manually on the hosts. Alternatively use veyon-cli (which is part of the veyon-service package) e.g. to import a configuration file.