Hello Aspirant,

As it is Saying "invalid credentials", which means you must have entered wrong user id or a wrong password for login. kindly provide correct login credentials it will be ok. If it is not working, then you could go for password reset.

Here i'm providing the answer key - https://news.careers360.com/nta-neet-2020-official-answer-key-released-at-ntaneetnicin

Official answer key- https://ntaneet.nic.in/ntaneet/ShowPdf.aspx?Type=E0184ADEDF913B076626646D3F52C3B49C39AD6D&ID=CB7A1D775E800FD1EE4049F7DCA9E041EB9BA083

Hope You get it :)