Step 1 : Go to This Website : https://10minutesemail.net/
and if you see an Temporary Edu Mail then follow next steps, if you don’t see an email with .edu then simply click on Delete icon Unless you get temp .edu extention.
email should be something like this @edu.pl
step 2 : go to https://www.canva.com/edu-signup
and sign up with that temp email, verify Email account.
After confirming you can edit temporary email to your gmail account directly from canva
Edit Account from here : https://www.canva.com/settings/your-account
Note: Use any other mail except the primary main gmail account.