You can follow this article to connect your Microsoft accounts to Instantly.
Free Outlook accounts (hotmail.com or outlook.com email addresses) are no longer allowed to be connected. Microsoft has a very strict policy about sending cold emails through free accounts.
Step 1: Go to Azure Active Directory
Here are the steps on how to set up your Microsoft 365 Azure account.
Click Settings within the Inbox and select Admin Center.
Click Show all and select Azure Active Directory.
Select the Properties tab.
Step 2: Allow the Inbox to use SMTP and IMAP
Next step after going to the Azure Active Directory, you may now proceed to allow the inbox to use SMTP and IMAP.
Here are the steps to enable SMTP and IMAP for Microsoft 365 Azure accounts:
Go back to Admin Center and select Users and click Active Users.
Select the inbox you want to add to Instantly.
Select the Mail tab and click Manage email apps.
Check IMAP and Authenticated SMTP.
Once you've completed, wait for an hour to be able to connect your account to Instantly.
Once you've completed the above steps, you will be able to connect your Microsoft 365 Azure accounts to Instantly!