Our new federated login system (SuperId) have been used for all new tenants in SOD since March 2018.
Read more about SuperID concepts here
Earlier today we migrated a lot of old partnersites in SOD to SuperId, and this means you may now try to configure single sign on by following the description here: https://community.superoffice.com/en/technical/documentation/prepare/crm-online/superid/configureIDPforSuperID/
Do note, the article is written for the production environment (online.superoffice.com), and you'll need to use the following url to register your identity provider for the SOD environment: https://id-sod.superoffice.com/identityprovider/register
The login dialog for SOD have information about the change and we would like to get your input if you experience any issues logging in now.
Also - if you have any questions, please post them here so more may benefit from the answer as well.