As per common policies, Teams needs MFA / 2FA (Multi / two factor authentication) on your M365 tenant to authenticate you on any device. Many of these authentication also relies on the fact your device is registered into this M365 tenants, and this is done by Intune device management.
This also means your personal device will need to be registered into this tenant. So many companies and employers (like mine) will put this as a strict policy.
I hope this clarifies your question.