The FAQs moved to Support Center

To login to to Support Center you use your WebKey account you also use to login your MindSphere tenant.

If you user is associated to a Site you can access the MindSphere content and see, edit & create support cases.

1. Ask your tenant owner to provide your tenant's Sold-To ID (Site ID) and WebKey Access Code (WAC). When a tenant is created, this is sent to the tenant owner (stated in the tenant order form). The e-mail is from "DF MindSphere Provisioning <provisioning@mindsphere.io>", Subject: "MindSphere - Upgrade your Support Account for your Tenant". 
2. Go to the following page: https://account.sw.siemens.com/en-US/sites/join
3. Enter Sold-To ID (Site ID) and WebKeyAccessCode

Solution B

Ask your tenant owner (stated in the tenant order form) to invite you directly from Support Center. There is a how to video posted here if your admin has not done this before: Site Administrator - managing users