Yes, this is pretty confusing. The same for usnake - it asks for user/password, but it is unclear where do you get them from.
I suppose the right way is to sign up first in web wallet, then to log in using those credentials both to uwallet ant to usnake. At least this is what I did, and it worked
I did sign up for the web wallet and I tried to use that info to login but it does not work for me. I tried two different email address/password and it did not work either time.
I just did this all once again to test it (with my another email address), and it worked beautifully. Steps are:
1. Go to Web uWallet, press "Sign up", enter any email address belonging to you, and any password (not the password of the email account!)
2. Login to the email client, find the confirmation mail, press confirmation link, then log in when redirected to webwallet.
3. Download the Windows uWallet (I use Windows PC), enter the email address and password. Do not press enter (it woesnt work, BTW, so this is a bug ), then click on "Sign In" button.
4. It gives a message box saying something like "successfully authorozed" and voila, you get the same address as in webWallet.
Maybe you missed the point 2?