I have been asked a lot regarding ways on how to sign up for Power BI if you do not have a school or work email. If you try using gmail, hotmail or any other known domain, Microsoft will identify it and it will not let you move forward.
If you are still in school or if you still have access to your .edu account, that should do the trick. However if you do not have access to neither school or work emails, as a solution for that would be a temporary email.
There are a lot of websites that offer services like this. What this basically means is that, there is a random email which is generated and will be available for use in the next 10 minutes, which email can be used as an email for sign up for Power BI. There will be a inbox folder and you will receive the confirmation email there.
As an example, if you go to tempmailo.com, it will show you a screen with a randomly generated email. Copy the temporary email you see there and use it in the sign up process for Power BI.
Go to Power BI SignUp page, copy paste the email there and click Next. You will see the screen below.
As you can see, Microsoft will send an email to the email used for sign up with a verification code to confirm that the email used is yours. If you will go back to the temporary email site, you will see the email received. Copy and paste the code to the verification code field and voila! you are all set.
Please note, there are a lot of other sites who offer temporary emails. Just google it and choose any from the first page results, it will do the trick. Here are some of those websites for your reference.
Cheers!