Multi Level Login 2

I get a chance to looking for solution about multi level login 2. The following is a screenshoot from multi leve login 2 :

I just write Joe as username and banana as password and then press 'Enter'. After that I get a page like below :

In this page, we ordered to Enter TAN #1. I was writting 15161 according on the introduction above.

On the next page we can see first name, last name, credit card type and credit card number, but no success sign in this page. I just logout with link who there. Then, I try to login again with same username. On the next page we ordered to Enter TAN #2. We can fill it with 4894 according on the introduction above.

On the next page we can see first name, last name, etc.

I tried to do same way until I have filled TAN #4. But, in this page, I tried to do tamper with this process and the result like below :

In the parameter, I can see the hidden user is Joe. Then, I tried to change hidden user with Jane. In the next page we get success sign with the sentences like this "Congratulations. You have successfully completed this lesson."