SimpleSAMLphp is a third-party PHP application that deals with authentication. The main focus of SimpleSAMLphp is providing support for SAML 2.0, but it supports a wide range of other protocols, such as Shibboleth, CAS, OpenID, WS-Federation or OAuth.
More information about SimpleSAMLphp here: https://simplesamlphp.org
Make sure you install it on the same domain and subdomain as FileRun, so that FileRun ca access the same browser cookies as SimpleSAMLphp. If you are unsure what that means, just install SimpleSAMLphp in a subfolder inside the FileRun installation folder.
Once you have configured SimpleSAMLphp with your identity provider, test your settings, and make sure you can sign in successfully, and that you are seeing the user information, like in this screenshot:

You can easily activate and configure the plugin directly from FileRun's
control panel, under System configuration →
User login and registration.
Using the attributes you are seeing inside SimpleSAMLphp, configure the FileRun mapping.
As per the example screenshot
Username attribute mapping would be samlLoginNameFirst name attribute mapping would be givenNameLast name attribute mapping would be surNameE-mail attribute mapping would be emailAddressGroup names attribute mapping would be memberOfBut the attributes returned from your identity provider can be completely different. The above is just an example to help you understand how the mapping is done.