Hi Don,
I thought you were looking for Capella 5.0 in this thread (Update Sites for Version 5.0), not specifically for “update sites”.
I am not 100% sure of what you are trying to do, but I would advise you to download and unzip it directly from the Capella 5.0.0 bundle from the Capella download page (https://www.eclipse.org/capella/download.html). I do not believe the number one use of using update sites are “to keep up to date with the software”, but rather to be able to install it with other software already installed.
Anyway, if you still want to use the Capella update sites, you’ll find them in the first post on this thread from Philippe, on this page: https://github.com/eclipse/capella/releases/tag/v5.0.0
Stephane LACRAMPE
Obeo Canada