Premiere Pro 2020 v14 Is Unable To Access Preferences Folder and Load Third-Party Audio Plug-Ins

I have come across the same issue. By doing some research I found that it had something to do with Disk Permissions, which once sorted fixed the issue. I'm running on Mojave 10.14. Follow this tutorial to get your permissions right and working: Repair Disk Permissions on Mac OSX 

are these 3rd party plug-ins?  If so, they may not be compatible with cc2020 although I think you indicated that they work on your desktop machine in 2020.  After you've changed permissions, and you do a get info for the plug-ins folder, has it updated correctly?  Can you save or move a file into that folder (which would be a way of testing permissions)?

macs can have issues with permissions.  Can you find where the plug-ins are located and control click on the containing folder and choose "get info" and look at "Sharing and Permissions" at the bottom of the get info window.  Make sure you have full read and write permissions.  You'll need to click on the lock icon at the bottom of the info window and put in your password to change things.   Once that's done, you'll have to click on the gear icon below and click on "apply to enclosed items."  

Sometimes this can be difficult to fix...  Post back if you have trouble with this or if it doesn't fix things.