Maybe ???? Although I'm just a Mac user here same as you (and everyone else here)and I don't work for Apple or Microsoft and haven't been trained by them.....try this link:
https://support.microsoft.com/en-us/office/i-can-t-send-or-receive-messages-with-outlook-for-mac-57c6d42c-3a4e-4f93-914a-212efe650a04,
also please bear in mind that the default Email protocol for Macs from Mojave on up (the more recent ones) is IMAP and NOT POP or POP3, as IMAP lets you use email with multiple devices....--
--could you save the document/thing in MS 365 you're working on, then compose a regular email and attach the file. or document, and then send it the usual way in Mac Mail ?? ....
and there's this link to Outlook which may be related to your problem, especially on the Mac:
https://techcommunity.microsoft.com/t5/outlook/outlook-for-mac-does-not-include-attached-files/m-p/3836961
So.... seeing as how you're using a Microsoft Product, in this case, Microsoft 365, and I don't know much (if at all) about Microsoft 365, the best way to get some help, would be to post on the tech community forums on Microsoft then go to "Outlook" then "General Discussion" ...you'd probably have to register or at least sign in there before you'd be able to ask questions/get help related to Outlook and Microsoft 365 on your MacBook Pro running Ventura.... which is Mac OS 13....
John B