ADE (4.5.4) crashes on launch despite several uninstalls/reinstalls [MacOS v10.11.6]

I'm not too sure if this problem has been posted and resolved previously. I'm on MacOS El Capitan (v10.11.6) on MacBookPro (Late 2008) if it helps.

I installed the latest (4.5.4) version of Adobe Digital Editions (ADE) and something went wrong with what I did (I seriously don't remember it now) and it crashed on subsequent launch. I later uninstalled that version, emptied the trash, and downloaded/installed a fresh copy, which again crashed on launch. This time though I repeated the cycle and followed the instructions from this URL: Installation issues for Adobe Digital Editions 4.0 but it hasn't resolved the issue.

I'd definitely appreciate if someone could guide me to a clean(er) uninstall and a successful reinstall of ADE. I'm getting anxious for not finding the root cause.

Bhooshan