Edit: I contacted the vit through email and then through phone.They said that it is okay to affix the photo and keep the signature on the e-admit card printout through slot booking.Thanks for your answer.

Dear Djeeru, now VITEEE slot booking process is in progress. This is only for candidates who have successfully completed filling their application. Though you have made the payment, because you havent completed filling the application form, you cannot qualify for slot booking. Your application process ends here and you cannot complete it now. The last date for filling the application form has been closed.