WhenIsGood works really well even if you don't have a user account - but there are advantages to creating one.
The main one is that you get to manage lots of different events and responses in your account dashboard.
If you are not logged in to an account when you create an event, the system will supply you with a "results code". You'll need this after people have responded so that you can see the matching times. If you organise lots of events, this means you need to keep track of lots of different results codes.
With an account, this isn't needed. You just log in and access any results from your dashboard. Events with responses have a link alongside called something like "3 so far".
There is no password. Click 'login or register', enter your email address, and we email you a six-digit code to type in. The account is created the first time you do this. Any earlier events that sent their alerts to that address are added to your dashboard when you first log in.