Your channel's iPhone and iPad player comes as a ready Xcode project. Apple only accepts apps built in Xcode on a Mac, so you open it there, upload it to App Store Connect under your own developer account, fill in your store page and send it to Apple for review.
Apple rewords its screens now and then. If a label below doesn't match yours exactly, look for the one nearest in meaning.
Why it has to be your account: Apple accepts apps made from a template only when the owner of the content submits them (guideline 4.2.6). Your channel, your account: that is exactly what Apple asks for.
No Mac at home? Any Mac that runs the current Xcode will do, including a Mac rented by the hour in the cloud. You only need it when you upload a new version.
Bundle ID not in the list? At developer.apple.com, open Certificates, Identifiers & Profiles → Identifiers and add it exactly as your control panel shows it.
The project already tells Apple it uses no special encryption, so the build won't stop at an export compliance question.
The app icon comes from the build itself, so there's no icon to upload here.
The app plays your live channel. When you're off air it shows "We'll be live soon" and starts playing by itself as soon as you go live. A reviewer who opens it during a quiet hour sees only that screen, and may reject the app as incomplete.
Apple turns away apps that feel too thin to be worth installing (guideline 4.2, minimum functionality). A player for one channel can draw that question, so your notes should show the reviewer what the app is for and what it does.
Make the channel page full: the app shows your logo, description, website, socials and contact details from your channel profile. A complete profile makes a richer app, for reviewers and viewers alike.
Later on: your stream, description, logo, links and contact details come from your channel profile, so changing them needs no new version. To change the app's name or icon, build the iPhone app again, upload it as in step 5 and submit a new version.