I'm working on using SSO with the embeddable widget. So far, I've gotten the OAuth process working through the PHP SDK, and can get an access_token, etc. for my sandbox application. But when I then load an Iframe with the embeddable app.html URL + authMode=sso + my sandbox appKey + appServer = https://platform.devtest.ringcentral.com, everything just redirects to https://ringcentral.github.io/ringcentral-embeddable/redirect.html#error=login_required
The application is not published, Platform Type = Browser-based, and has two OAuth Redirect URIs configured -- my callback endpoint for the OAuth process on the server, and the default embeddable redirect URI https://ringcentral.github.io/ringcentral-embeddable/redirect.html
Any ideas?