Hey @giuliaester,
Welcome back to the community and thanks for taking the time to post your issue on the forums.
I'm sorry that you're having issues with creating a new account, the reason would be that your email address is still associated to your former account.
If you use a different email address, that would work but if you want to use the same email address, I will take some details via a private message and I can arrange for our support team to remove the email address that will let you re-register for your online account.
Please let me know, if you want to keep using the email address and I will send a private message over.
Regards,
Steven_L