Problem Adding a User

I created a CRM account for our company and I wanted to add another person to it. However, when my college opens the invitation she should type in a passwort to continue. But I don't know what kind of passwort that should be. My college doesn't have an account yet so she creates her own passwort. After she does that, there appears to be an error we don't understand.

Anybody can help me with this problem?