Article 5 (as most of the constitution) was directed primarily against the Catholic Church...a Religious Order would be a group of adults getting together to try to live the gospel with a particular emphasis, say, education...they generally would live together. In the Medieval ages and in Mexico, these groups owned property and became QUITE powerful.
Not trying to support the JW's here, but just because a "constitution" grants a right doesn't mean you get that right in practice. The Chinese and Vietmanese Constitutions grant Freedom of Religion, but try to practice outside of a state run church.
Still, the issue is about as put forth here...the JW's could worship freely or own property, but not both.