If you've signed up to be a test taker at Usercrowd.com but you actually want to create and run tests as a researcher, you won't be able to sign up at Usabilityhub.com with the same email address you have used for your Usercrowd account.
You've got a few options:
Sign up to UsabilityHub with a different email if you have one
If you signed up to UserCrowd with your personal email, you can sign up to UsabilityHub with your work email. You'll then be able to take tests as a panelist and also create tests of your own to send out.
If your email is via Google, create a temporary alias
If your email is hosted with Google, you can create a temporary email alias by adding a + or . symbol to your email address. For example, if you used your email "firstname.lastname@example.org" to sign up to UserCrowd, you can sign up to UsabilityHub with "email@example.com" or "firstname.lastname@example.org". Both of these will work - you'll just need to make sure you save your login details
Otherwise, contact us to convert your UserCrowd tester account to a UsabilityHub creator account
If you don't have another email, simply contact us via email at email@example.com and we will convert your account. You will no longer have access to UserCrowd if you do this.