ACR 11.2 freezing when opening files

Last night I tried to open a DNG file from my Pentax K-1 for the first time since updating ACR from 11.0 to 11.2 , the import pane showed the image , but the sliders were unresponsive , I could not close ACR , nor could I force quit out of PS . In the end I had to shut the computer down by holding the power button .

The computer is a MacPro 3,1 from 2008 , with 16Gb RAM and running OS 10.11.6 El Capitan , the highest supported . I can still open the same file in Lightroom , and it also opens on my MacBook Pro , running same OS and version of PS , but still on Camera RAW 11.0

I was looking for a way to revert back to the earlier version of ACR , which was working fine for me . I uninstalled PS , then went back to install PS CC 19.0 instead of 19.1.7 . After uninstalling , ACR had disappeared from my list of installed Apps , but on installing 19.0 , I ended up with ACR 11.2 again .

I have since uninstalled both PS , LR and CC , and am now downloading the installer for PS 18 from the legacy page in the hope this will bring me an earlier version of ACR .

I've trawled through the support pages , but can only see links to much earlier versions of ACR . Can it be installed separately , Or is there another way of getting back to PS 19.1.7 and ACR 11.0 ?