For username you can just use the email address you created the account with, for password select the "forgot password" option on Ezviz website and enter the email address ou created the account with, they will email you a password reset link.
If you can't remember the email address you created...
Hi I am a dahua distributor here are some of their cameras which can work standalone they support memory card and cloud storage - http://www.dahuasecurity.com/products/productSelector