Did you see this?:
https://inmusicbrands.force.com/BFDHelp/s/article/BFD3-BFD-3-4-1-11-Installation-Trouble
I have and I've attempted that. I get the following error when I try to install, which is crazy because I don't even have ProTools installed, never have on this machine, and don't even have the referenced folder. I've even tried creating it with a blank file, and still get same:
Error deleting BFD3.aaxplugin. Please ensure Protools isn't running, or delete /Library/Application Support/Avid/Audio/Plug-Ins/BFD3.aaxplugin manually, and try again. This installation will now abort