Can I use Spanbox without creating an account or giving my email?

No, Spanbox itself needs no account and no email, there's genuinely no signup. You download it and sign into your own apps inside it. The only logins involved are your existing app accounts (Gmail, WhatsApp, etc.), done on their own pages.

No email, no signup, nothing. Download and go, which is also why there's no Spanbox account that could ever get breached.