I am the System Administrator for a software company and while implementing SSO for many of our corporate applications, I came across Intacct. There is documentation from Duo located here: https://duo.com/docs/intacct. There is one thing to note that I did not see in the documentation, which occurred while setting up and testing SSO for Intacct: the “Federated SSO User ID” is case sensitive. Now, I tested this with multiple users to confirm, as well as flipping back and forth between case sensitive and normal. I can confirm that Intacct requires that the Federated SSO User ID be exactly as it is found in Duo. Hope this helps someone else, as it set me back about a day until I sussed it out.