For app=marketplace, the gateway parses attributes and redirects to https://dev.nbm.store/ with query params (dev only).
SAMLResponse (required): base64-encoded, signed SAML 2.0 response containing:
memberId, email, city, state, fname, lname.
app (required): must be marketplace → /gateway/acs?app=marketplace.SAMLResponse at /gateway/acs?app=marketplace.https://dev.nbm.store/ with:
?memberId=...&email=...&city=...&state=...&fname=...&lname=....