If two Protestants, married in a Protestant Church, get a divorce, could one of the parties marry a Catholic in the Catholic Church provided he or she becomes a Catholic?

No. The marriage of two Protestants in a Protestant Church is valid before God, and nothing can dissolve that marriage except the death of one of the parties. Divorce does not give even such Protestants the right to marry again whilst both parties are still living. And becoming a Catholic has no effect upon the validity of such a marriage.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty