Hi!
don't worry as these  type of issues are commonly seen while Neet counselling. in this case students are advised to wait for some time and let the server cool down and you can try for counselling after 5-6 hours from some other device or the same device .The issue is expected to be solved by then if the issue is not solved even by then you can contact the NEET  officials via  helpline number or mail.
Neet counselling procedure you can follow the given link:
https://www.google.com/amp/s/medicine.careers360.com/articles/neet-counselling-faqs/amp

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