It is necessary to register to use this service. This is only so that your collections can be allocated to you. There is no cost. You will only be emailed about service issues.
After registering and signing in, you can view your user information by clicking your username on the top right menu. This includes your api_key, which you will need if you want to send data via the API.
Don't get your username wrong! We can't change it! (If you do, just create a new account for yourself.)