A client of mine would like to sign up to Power BI but he gets the "Your IT department has turned off signup for Microsoft Power BI" message. The organisation is not an O365 customer and they don't buy any Microsoft products through an MS partner. The organisation is a mature startup with virutally zero centrally goverened IT (the only functionality that isn't do it yourself is email, provided by Google). Some users have purchased Office 365 independantly (under the Small Business / Home plans etc) but otherwise there shouldn't be an organisation wide Office 365 tenant, much less a Global Admin.
So how might I go about finding the O365 admin login details, changing this setting and enabling sign-up?