For vanilla ubuntu gnome the following worked for me.
1.1.1 In this new folder double click on SweetHome3D file and choose „Execute”; Will show up a new SH3D project
The execute step is the one shared in the downloads page by @puybaret
https://askubuntu.com/questions/286621/how-do...table-scripts-in-nautilus

Following from here: https://howto-ubuntunew.blogspot.com/2017/10/...ll-sweet-home-3d-552.html on ubuntu you can create a desktop so that you can find it on dash.

$ sudo gedit /usr/share/applications/sweethome3d-6.3.desktop

[Desktop Entry]
Version=1.0
Name=Sweet Home 3D 5.5.2
GenericName=Interior 2D design application with 3D preview
GenericName[de]=Innenraumplaner
Comment=Interior design Java application for quickly choosing and placing furniture on a house 2D plan drawn by the end-user with a 3D preview
Exec=/home/andres/SweetHome3D-6.3/SweetHome3D
Icon=SweetHome3DIcon
StartupNotify=true
StartupWMClass=com-eteks-sweethome3d-SweetHome3D
Terminal=false
Type=Application
Categories=Graphics;2DGraphics;3DGraphics;
Keywords=interior;design;2D;3D;home;house;furniture;java;

Special precaution on the Exec line as you might have used a different location. you can find the file mentioned in step 1.1.1 above and copy it. when you paste it in gedit it will past the full path, saves form typing mistakes.

for the icon right click in the folder where the png is located (again step 1.1.1. above).

$sudo cp SweetHome3DIcon.png /usr/share/icons/