Greetings Sivananda!

Hope you're doing great

I hope you have applied for Jee advance paper separately. If not, you won't be able to get admit card or appear for the Jee Advance paper. Now, if you've applied and even after providing all the details you can't access your admit card then you should first reset your password. Sometimes the password assigned by the examination body is so dynamic, we unconscious create two passwords and save the previous one. 

There can be chances that the documents you've to upload might not the adequate or incorrect so they decided to cancel your candidature. Contact the zonal IIT office if that's the issue and get the issue resolved as early as possible. The server could be a possible reason why you're unable to download. Make sure your internet connection is working. Also, there are many students who might be downloading the hall ticket at the same time, there can be a chance of server not working. Try download after 6 pm in the evening.

Even when you're unable to access then, you should write an email mentioning your issue as a subject to the grievances redressal team, the email id and contact no. is available at http://jeeadv.ac.in

Hope this will work and your problem will get resolved. If not, do reach out in the comment section, will be glad to help you through different proceedings.

All the best for your exams!