exchange password error: the below keeps appearing. How do I get rid of it?

Some email providers now require the use of App Specific Passwords when accessing mail over IMAP or POP3. If this applies to your email account, you will need to generate a unique password for your iPad email account - that will differ from your normal Account Password. As examples - Microsoft, AOL, Yahoo and Google all use App Specific Passwords when using anything other than their own email client Apps. 

Microsoft accounts include live.com, outlook.com and hotmail.com domains.

If you need to generate an App Specific Password, you’ll need to log-in to your Mail Providers account management webpage - using a web browser - and generate the Password from the appropriate account security page.

More details about Microsoft App Passwords can be found here:

https://support.microsoft.com/en-us/account-billing/using-app-passwords-with-apps-that-don-t-support-two-step-verification-5896ed9b-4263-e681-128a-a6f2979a7944