The script defaults to impersonating an Office365 Azure based SP. Override by specifying the EntityID of the SP you wish to impersonate in the ```ENTITYID``` environment variable.
You also need to specify the registered endpoint that the request is pretending to come from. Again, this defaults to the Office365 endpoint. Override with ```ENDPOINT```.
You **MUST** specify a ```URL``` to make the request against. For a Shibboleth IDP this probably looks like ```https://idp.example.com/idp/profile/SAML2/SOAP/ECP```.