yes you can still fill the Neet Pg Form 21 for md ms go to the link and register in NBE website

The eligibility to apply for NEET PG is as follows:

• Educational Qualification - Candidates are required to possess MBBS degree or Provisional MBBS Pass Certificate recognised by Indian Medical Council Act 1956

• Certificate of Registration - Candidates must have MBBS qualification registration (permanent/provisional). This registration is supposed to be issued by MCI or State Medical Council (SMC) or Medical Council of India (MCI)

• Internship - As per the eligibility criteria of NEET PG candidate must complete their one year internship on or before March 31, 2021

The eligibility clearly states that you must be registered under the MCI or your state medical council. It is better to get yourself registered or have your license renewed.