OpenCart 2.1.0.2 - Trouble with OpenBay Pro eBay app

Our site is hosted elsewhere, but I installed the OpenBay Pro extension today which subsequently crashed the site when I installed the eBay app through the OpenBay dashboard. After speaking with the guy that created the site for us, he says it's related to this:

viewtopic.php?t=153069

which recommends erasing a line of code to get the site back up quickly. Naturally, this disables the app and gives the error:

Notice: Error: Could not load model C:/Sites/*COMPANY_NAME*/Website/admin/model/sale/customer_group.php! in C:\Sites\*COMPANY_NAME*\Website\vqmod\vqcache\vq2-system_storage_modification_system_engine_loader.php on line 63

Honestly, I don't really know too much about any of this - I just want an easy way to manage my site and store. Is there an easy way to get OpenBay working with this version of Open Cart?

Sorry if this has been covered before, I did search but no-one seemed to have the exact same error as myself.

I really don't get why people almost always tend to ask questions about modules' related issues, here on the forums, instead of directly contacting the developers of those modules