at that time I checked it, and adding information to the profile and filling in the number worked correctly. Could you please tell me what country number you are using?
Now profile information can be saved after filling in some details and a pop up will appear to save it.
But it's not possible to verify the number when using the +62 country code. In fact, I don't want to use the number if it's an optional option.
I had the same problem and I wrote to their support about it. Their support asks for some time so they can fix it. If you do not verify your phone number, you won't be able to complete your profile. You won't be able to claim the free spins promo without completing the profile. So you have to choose one. Either compromise the anonymity to get the bonus, or you have to leave the bonus.
By the way, their website design looks familiar. I feel like I have seen a similar template before but I cannot remember which one. I liked the template anyway, no complain about it. I hope they will improve user experience.