We don't recommend Outlook 2016 for KUMail because even the latest version doesn't support OAuth authentication. Please consider using another OAuth-capable email client such as the latest version of Outlook 2019.

Google provides G Suite Sync for Microsoft Outlook (GSSMO) to let you authenticate with Shibboleth in Outlook 2016. However, we don't support GSSMO and still recommend that you upgrade to Outlook 2019 or others. If you wish to use the software nevertheless, please do it at your own risk.