Problems with Mirror copy.js

I posted to the script's thread, but it's pretty old, so I thought I should ask here as well. I can't seem to make the script work in Mojave 10.14.6 with C3D 7.4.2. Nothing happens when I run it. I last successfully ran it back in March. Why isn't it working?
I'm not sure why it isn't working if it was before. If you had just installed it, I'd say check with folder it was put in. But since it worked before for you, that shouldn't be the problem. There is a newer Beta version though. I have 7.5b1. It's not on the website. It was only posted to the forum. Let me see if I can find the link.

You can find the newer beta version at this link:

Maybe it will solve the problem?
Sorry I didn't respond sooner (a year sooner, hope you're doing well). Yes. I guess I expected to choose the script from the script menu and see the mirrored copy without taking any further action. I still see an error message after executing. I'll take note of it next time, and then ask for help again. Thanks.