I was offered a job as a cartographer, but how do I get started?

I am terrible with mathematics, algebra, and all those things. I got an offer to become a cartographer for a group of worldbuilders for a fictional world. We discussed things in private with the leader, but I have a ton of questions. We agreed to the terms, and I am so excited. I am so excited, but I am still worried I might be fired since I'm not familiar with anything. I have to work with so many people, which makes it scarier. I'm so nervous and flustered about it, and I don't know what to do. I've been in private contact with so many people, and I'm still confused on how to do things. I am very on edge, but I really do want to help. I want to learn, but how do I start?