Mixing Modules, and Extensions

Hi -

A couple suggestions:

As for the extension catalog it should be available. Maybe these links will help you debug.

https://discourse.slicer.org/t/trouble-with-extension-manager/2457

https://www.slicer.org/wiki/Documentation/Nightly/SlicerApplication/ExtensionsManager#How_to_manually_download_an_extension_package.3F

Hope that helps.