Visit https://flatpak.org/.
I followed this doku.
Use this config file.
or enter this command flatpak remote-add --if-not-exists jdm https://flatpak.jdmweb2.ch/jdm.flatpakrepo
Use flatpak install jdm org.kicad.KiCad/x86_64/7.0.11.
Use flatpak install https://flatpak.jdmweb2.ch/appstream/org.kicad.KiCad.flatpakref.