SAML used to be the most populare specification for federated authentication. Nowadays, modern applications tend to use OpenID Connect. Nevertheless, idaas.nl has excellent support for SAML. This protocol is still widely used, especially for enterprise applications.
Read the documentation on how to configure SAML.
The SAML Metadata of the master-tenant can be found under https://login.idaas.nl/saml/v2/metadata.xml.