You can read the report of the committee for yourself.
In the summary of findings we do read that
Scientific acoustical evidence establishes a high probability that two gunmen fired at President John F. Kennedy. Other scientific evidence does not preclude the possibility of two gunmen firing at the President.
Based on this they state
The committee believes, on the basis of the evidence available to it, that President John F. Kennedy was probably assassinated as a result of a conspiracy.
However all it means by that is that they believed more than one gunman was involved. (Two people getting together to commit a crime is automatically a 'conspiracy' in law.) The report summary states explicitly that the main organizations accused of conspiring to kill Kennedy were not involved. This includes the Soviet government, the Cuban government, anti-Castro Cuban groups, the Mafia, the Secret Service, Federal Bureau of Investigation and Central Intelligence Agency.
With regard to the Warren Commission, the report states:
The Warren Commission conducted a thorough and professional investigation into the responsibility of Lee Harvey Oswald for the assassination.
The Warren Commission failed to investigate adequately the possibility of a conspiracy to assassinate the President. This deficiency was attributable in part to the failure of the Commission to receive all the relevant information that was in the possession of other agencies and departments of the Government.
The Warren Commission arrived at its conclusions, based on the evidence available to it, in good faith.