Questions about Affiliate Partner Program

Hello,

I am interested in the Affiliate Partner program and would like to sign up for this. However, the sign-up form seems to meet errors because I have tried to fill the form many times but it all failed. 

The link I used: https://www.booking.com/affiliate-program/v2/index.vi.html

When I completed step 1, I chose "Next step" button, but it just came back at the beginning. Therefore, I cannot move to step 2 and 3.

Please check my case and what should I do to sign up successfully? 

Many thanks!