Mail server error that "You can't log in to the server. Probably the username..."

Hey, I’m trying to create a local e-mail for users to circulate correspondence in the company’s local network. But when I add a user to Thunderbird, I get an error that “You can’t log in to the server. Probably the username, password or configuration is set incorrectly. Please help, I’ll give you all the ss with the settings, if there’s anything else missing, I’ll send it to you.”
Zrzut ekranu 2023-09-30 125910Zrzut ekranu 2023-09-30 131825