A brand account is an account that is specifically for your company’s brand. This account is different from a personal Google account. Multiple people can manage brand channels, but not personal Youtube channels. If you see Add or remove manager(s), then the YT account is a brand channel and you’re good to go. If you don’t see that, follow these instructions.
To successfully move your YouTube channel to a Branded channel, please follow the steps in this video: https://www.youtube.com/watch?v=00Le1o5A2a0&t=13s
After you’ve successfully moved to a brand channel, please add firstname.lastname@example.org as Manager. You can refer to How to Add Madwire as a YouTube Channel Manager.