Through firmlinks, the two volumes are made to look like a single volume. If you were asking how this relates to the much newer separation of the macOS system into separate read-only partition and read/write Data partition, I don’t think that changes anything either, because the Data partition is hidden in the Finder.

Although I am finding a lot of profile installation instructions have not been updated since then.

Yes, that reference is for 10.7 because that's apparently when the permissions on /Library were tightened up, and that has not changed…it is still in effect in macOS 10.15 Catalina. I suspect that this is an OSX issue given that the problem exists in both Adobe and Canon software but I thought readers of this forum might have run into the issue and found a solution. We also downloaded the profile again using a different browser to rule out profile corruption during download. We have restarted all the relevant applications and restarted the computer. He had previously deleted some profiles for a printer he no longer owns but they still show up in Lightroom's list (as well as the other apps). In fact, the list of available profiles that appears when you select Other from the profile drop-down menu in Print or Softproof, does not match the list of profiles in the Colorsync folder.

Library/Colorsync/Profiles/ but it is not showing up in Lightroom, Photoshop or the Canon Print application that came with his Canon Imageprograf 2100.

I have a student who has run into a strange anomaly in Lightroom Classic and Photoshop CC 2020 in Mac Osx (all are current versions).

How to install icc profile photoshop