Need help integrating Prismic with Jekyll on Vercel

In short: a client of a client has a Jekyll site, hosted on Vercel and content managed by Prismic. The previous dev company changed focus and abruptly dumped support for him, gave a zip file with site and said to set everything up himself. Said it should be straightforward.

Well, the github repo connects with Vercel and builds the site, but I have never used Prismic and for the life of me can not figure out where and how to reconnect to the existing Prismic repo (provided it is even possible, as the original dev said).

The data is still on Prismic, as direct links from config files show images, but can't get them integrated in the built site.

Any help greatly appreciated and let me know what information I need to provide.

EDIT: I guess my real question is - is it actually possible to transfer Prismic repo ownership?

Hello @reinis.ikass, welcome to the community!
Yes, it's possible to transfer ownership of your repo to someone else. You can do this youself, in your repo settings: