The POST /{envID}/saml20/sp/acs?RelayState={samlAppID} operation is a service provider (SP-initiated) SAML single sign-on flow that passes the application ID and (optionally) the application URL in the RelayState request parameter.

The RelayState parameter needs to be in the URL-encoded format of applicationId=<your-appID>. For example: RelayState=applicationId%3D280686bb-cfca-4825-88a1-67dc1c89c73c, where “%3D” is the URL-encoded value for “=”.