I am posting this here as this may be useful to users wanting to install Acceleo 3 on Capella 1.3.
First, download this Acceleo version which is the one aligned with Capella 1.3 dependencies:
Use the zip instead of the update site as sometimes network issues/firewall/mirrors can make the update fail.
Then you should select the following to be installed (see attached image)
Then you should be good to go. Hope this helps!