I know how to do attachments, but, everytime we try it try to attach from microsoft365, on a new computer, we do not have microsoft 365 installed!
Do you have a local installed program set up for receiving or sending emails, e.g. Thunderbird, Windows Mail, etc.?
If you only ever use a web browser for emails then you will need to save your file, then attach the saved file from within your web browser using the method for your online access.
For my own use, I always save the file and then attach the file from within the email program. I regard document creation and document distribution as two separate independent jobs.
Duplicate at 310028/we-use-opera-and-microsoft-edge-and-cannot-attach-a-resume-from-libreoffice-63-to-aol-hotmail ?
Save the file to disc. Open your email program/web browser at your email location. Create new email and look for Add Attachment (possibly a paperclip icon) to attach file. Click on Add Attachment, navigate to your saved file, select it and OK (or whatever button will upload the file)