Start here if you already have an Organizational account.
Step One: Navigate to the Power BI Community and click Sign In as normal.
Step Two: You’ll be sent to a temporary page notifying you to link your Community account with your Organizational account, as seen below. Click “Sign in to your organizational account.”
Step Three: Enter your organizational email account, then click ‘Next'.
Step Four: You’ll then be directed to the following screen, similar to the normal Community log-in page
Step Five: Log in with community account, using your existing username and password. This step associates your organizational account with your existing Community credentials.
Done! You are signed into the Community.
QUESTIONS OR PROBLEMS?
Checkout these FAQs: https://community.powerbi.com/t5/Community-Blog/SSO-FAQ-s/ba-p/559224
Send us an email: PBICommunityAdmin@microsoft.com
When sending emails, please include as much detail as possible (i.e.: time and time zone, email address you have tried to link, browser, screen shots, etc). This will help us solve your problem more quickly.