This article will walk you through how to add a new user to your App Store account. We also have a video at the bottom of the article if you would rather watch that!
First, go to appstoreconnect.apple.com and log into your account. Next, we're going to navigate to the Users & Access page.
On the next page, click the little blue plus button to add a user.
On this form you will enter your user information. The first checkbox to check is "App Manager".
The next box that is absolutely vital to check is "Access to Certificates, Identifiers, & Profiles" under Developer Resources. This is what allows us to build apps on your account.
When you're all set checking those boxes, click invite!
That's all there is to it! Check out the video if you like!