I am on the app store connect page, looks like I can click to add a build to test amoungst beta tester.
How can I see how is in this group called, "outside Beta Testers"?
I've looked everywhere
It looks like one of two things:
If you click on the "v" next to iOS Builds you should get a drop down and if you scroll down, there should be a heading External Testing with the lists there. Then you can click on the list and see who is in it.
On my desktop, this isn't hidden, and everything that shows on the drop down shows to the left of the list of builds.
It's possible you don't have permission, but I don't think that's the case. You need Admin, Account Holder or App Manager role - I think you've probably got App Manager in order to get to that screen.