A few reasons. One, no one who ever filed a FOIA request ever got anything as a result. They've always been kept secret, which is what you'd expect from classified information. Two, despite having plenty of opportunity and despite being directly asked during the legal proceedings, Trump never stated on record that they were declassified, which is a pretty weird thing to do when your entire belief system is based on them being declassified.
Since the documents belong to the government, he does not have a right to them when he is no longer working for the government.
But again, you keep refusing to acknowledge that he received a subpoena for the documents and his refusal to turn them over, hiding them from the DoJ, constitutes obstruction of justice and is a crime.