Club admins and owners add players at the club level. A name is required, with email and a photo both optional. Adding someone here doesn't put them on a specific team straight away; you'll assign them via each team's roster afterwards. As a shortcut, you can also pick their initial team while adding them.
For a whole squad list at once, use the same CSV bulk import pattern as onboarding: map your columns, review the preview for row-level errors, then confirm. Name is required, while email and team are both optional. Including a team column assigns players across multiple teams in one go.