Team Group default permissions non-functional
For groups on a Team account, the group setting: Has [permission] access to this account's repositories, where Permission is: no, read, write, or admin, seems both extraneous and non-functional.
My experience is that for any group to have access to a repo, that group must explicitly be added to the repo using the Access Management feature of the repo. At the time a group is added, one must also set the group's permissions (read, write, admin) against the repo. The default group setting seems to have no effect.
If I create a new group on a Team account, and I set: Has Admin access to this account' s repositories. Members of that group do not suddenly gain admin level access to the account's repositories. As mentioned, the group must be added explicitly to individual repos, via the repo's Access Management feature, setting its permission level at the time it is added.