The other Mac's screen is locked

Tele can't unlock a Mac, but it tells you and offers a way in.

While another Mac is connected, the sharing Mac stays awake. If its screen is locked, Tele says so and offers Unlock with Screen Sharing…

That uses macOS's own Screen Sharing, and it lasts only while that session is open. macOS then locks the Mac again.

Tele never stores the login password.