It says free but it's not. Actually it's very expensive. It's just an app that i wouldn't pay a cent for it. Good luck with it
If you uninstall the app and a customer logs in then goes to /account/ nothing but an ajax loader displays...to fix I found the file snippets/pa-oc-overlay.liquid" and commented out the entire line...and voila I got access to my site again.
Should have known it was sloppily coded as they misspelled the product name 3 times in the description of their own app..."Optimise" checkout...