I haven't needed it since I bought my last camera. I do sometimes use the Sony utilities that go with the camera to trim fat from XAVC-S, though. Play Memories Home.
There are three different tools in the Catalyst Series, Catalyst Browse (Free), Catalyst Prepare and Catalyst Edit (both are subscription based). Prepare his a higher version of Browse and Edit is the NLE. I did play with the trial version a while back but was not impressed.
Subscription based. Feature poor. Don't see the point of it at all.
BTW The free Catalyst Browse installs an OpenCL emulation ("E-gpu") that MAY mess with GPU support on your system. (On my system it prevents FilmConvert using the GPU.)