In order to become a Phyxter Rewards member, you need to need to be able to complete a purchase through Phyxter Pro. One of the first steps to do so is by completing your profile - including your credit card info.
Basically, you can't earn points without making a purchase, and you can't make a purchase without adding your credit card.
So, once your profile is completed, your login credentials should work for Phyxter Rewards. To actually earn points, start making those purchases!