Hello Charlotte. The "autoreplies not supported" is part of the message you are seeing in outlook, which indicates that your outlook profile is associated with an account that does not support server-side automatic replies in the New Outlook for Mac. Server-side automatic replies are only available for exchange account types and Microsoft 365 accounts. For example, IMAP and POP account types cannot use exchange specific features like out of office responses. The replace00 label means that outlook could not map your account to a supported protocol for that feature, which probably means that your account is an imap or pop account.
To fix that it can be manually removed. You could try to log into the email provider’s webmail and disable the vacation or auto reply settings from there. A common one would be Orange or Wanadoo and if you have a gmail account, you could log in there.
If your account supports Exchange or Microsoft 365 you may try removing the account entirely and adding it back in as an Exchange account in Outlook. Go to Outlook > Settings > Accounts and remove your current account then re-add it by selecting Microsoft Exchange and your account credentials. You now have support for auto-replies, etc.
Here's the reference: https://learn.microsoft.com/en-us/answers/questions/4738789/conflicting-statements-regarding-outlook-for-mac-a
Best regards,