We have to block several users per day for creating multiple accounts. I can tell you no amount of wording on the website will work, people have multiple email

We have to block several users per day for creating multiple accounts. I can tell you no amount of wording on the website will work, people have multiple email addresses and many use burner/disposable/temporary emails for signup. As first line of defense add a captcha, then rate-limiting by IP address. Some download website have a counter "You can continue after waiting 10 minutes ... or upgrade now", that might work here.