You are trying to read emails from an Office Shared Mailbox, such as <account email address>\suffix (with the shared mailbox suffix).
But the Read Email Process Action is throwing an error such as "AUTHENTICATE failed":
Prerequisites: - Stambia Designer DI and Stambia Runtinme S20.2.0 or higher
To fix this issue, an additional property with KeyValue has been created on Email Metadata/Incoming account, to provide additional properties necessary to be able to establish a connection, with IMAP.
Thus, to read mails on shared mailbox, two of those properties are necessary: