These days iWriter.com is not accepting new writer sign-ups. But there is a software you can use to bypass that and create a new account. https://beta.iwriter.com/register-writer says "We are not currently accepting new writer applications at this time."
If you want to bypass this and create a new iWriter account, Click Here to get that software. It costs $15. Make your payment via paypal and after checkout you will be taken to the download page automatically. It is an automated process.