Please read the following carefully:
Use a valid, not 10-minutes/disposable, e-mail address, it is required for account activation.
The registration is ONLY successful if a green text is displayed on the next page.
The activation of the account can take up to 5 minutes, so please do NOT leave the activation page that you open via the e-mail. Otherwise the account including e-mail and subdomain will be blocked.
If you use a 10-minute/disposable e-mail address, the registration may fail (as described above) and/or your account may be blocked and/or deleted by the automatic system afterwards!

Have a first look at the cPanel (functions and appearance can vary): cPanel Demo

Not convinced yet? Then take a look at how your website looks after successful registration: testsite.epichost.xyz