Please make sure the following settings are correct for the account:
1. The account needs to be configured to allow IMAP access.
Individual Office365 users can make this update themselves but for those with a company account, the IMAP enablement will need to be completed by an IT administrator. To allow IMAP access on Office365, go to the Exchange Control Panel, click on "mailbox features" and enable IMAP from there.
2. The account needs to be configured to "Allow less secure apps". IMAP is considered "less secure".
3. If you have a 2-step verification set up then you need to turn it off or create an "App Password".
If you create an app password, use the app password in the "password" field in Aid4Mail.
Also please refer to the following articles for more assistance: