You filestoragesystem seems to be configured to local which is not compliant with a docker image.
And the SAML module needs an external file storage system to work (see module dependencies : If you are running your app outside of the Mendix Cloud, make sure you have external file storage configured. The SAML module writes configuration data to a file document on the file storage to read it later. Without external file storage, this configuration will be lost when you restart your app. The SAML module will not work correctly without reading the configuration data from the file storage). So you need to configure one to be able to use SAML module.
hope this helps