Hi, Norah_85. I am an independent advisor, trying to help other users in the Community with my experience in Microsoft products. Please note that I am a user like you and don't work directly for Microsoft.
To help show you how to add and request read receipts and delivery notifications via Outlook web, I pulled these steps from https://support.microsoft.com/office/e09af74d-3519-45fc-a680-37a538a92157
"To request a read receipt or a delivery receipt for your message:
Select the Three dots icon at the top of the message compose pane.
Select Show message options.
Select Request a read receipt or Request a delivery receipt, or both.
To choose how Outlook on the web responds to read receipt requests:
Select Settings Settings > View all Outlook settings.
Select Mail > Message handling.
Under Read receipts, choose how to respond to requests for read receipts."
I hope this helps, let me know if this contradicts what you need. I remain helpful in answering any more of your questions.
Best Regards,
Femi.