How can I restore a missing file in my Debut theme?

[ccallas]

I'm new to Shopify (taking over from a person who left). The store is using the Debut theme (version 17.9.2). When I try to access the shopping cart, get this error:

Liquid error: Error in tag 'section' - 'cart-template' is not a valid section type

The cart-template.liquid file is missing from the theme files.  No idea how it went missing and the former owner isn't available to ask. I'm hoping to find a replacement file.

I don't see where to get a fresh copy of the Debut theme files. Searching the theme store does not find Debut.  I found a Github repo that has Debut files, but I don't know where to get them officially.

I'd appreciate any help you can give.  This store is for a non-profit's annual sale, so it only gets used for a couple of months out of the year... and that time is coming up soon!

Thanks!