Working with Custom Theme

I have been asked to work on a theme that was developed for a customer. The customer worked with a company who worked with a developer and that broke down. So I have been asked to take over the project. I have written a theme and a few plugins, but am no real WP coding expert. To complicate things the theme was developed on Pantheon using Git. I am not a Git expert. To make changes requires going through several git commands each time a change something, which is tedious. So I tried to install the theme on my local machine, but it will not load on the front end correctly and I suppose this has to do with it is missing Patheon’s code. I did run a theme check and it shows a lot of warnings.

One of the things I need to fix is the archive page is missing the container. However, there is no archive page in the theme and I cannot figure out what page is rendering the archives.

Does anyone have any advice on this matter?