Libre cadd installation

How can I install Libre Cadd or draftsight in Endless

Endless uses a form of application package called Flatpak, which can be published into our App Center, or downloaded and installed directly from the application developer.

If you want one of those specifical applications (which don’t appear to be in our App Center), you should ask the developer of the app to provide it in a Flatpak for you. If you’re just looking for some kind of CAD program, there’s one in the App Center you can install right away, just search for “CAD” on the home screen and it’ll show up as a result under the App Center.