Cognizant — Regarding pre joining formalities offer letter

Sir /mam
iam 2021 passout 3 days back I got prejoining formalities mail first then I got offer letter mail .. after getting prejoining mail I followed the steps and created mail id same as which I previously get mails from cognizant. . I was about to complete my registration . after mobile authentication suddenly error page has displayed I tried various ways lot of times but no use plz help me out of this ..
CTS genc ( cvr College Of engineering Hyderabad)
my candidate id :15016007