I have downloaded the latest Slicer Windows Version 4.11.0 (Preview Release, revision 28433, built 2019-08-12). But when I went to Extension Manager, it showed that both “SlicerRT” and “SlicerElastix” cannot be installed. Does this mean these two modules will not exist from now on? Thanks.
These extensions are actively developed and maintained on both stable and preview releases. You can check their build status on the dashboard.
If the extensions did not show up in the extension manager then you might have tried too early in the morning. If you cannot wait for the builds to complete then you can download yesterday’s preview release using this link.