SSO still needs to authenticate to powerbi.com when you click the link. I don't remember if there is a "remember me" checkbox or not. The user doesn't have to enter the password for sure. I don't recall if it is mandatory to enter the email address or not - you could try without it. Most browsers will save the username anyway and auto populate this field. The sso should do the rest
* Matt is a Microsoft MVP (Power BI) and author of the Power BI Book Supercharge Power BI.