OK, then answer the question. If North Carolina and Rhode Island were not part of the Union then how did they become states without complying with the provisions for admitting new states outlined in Article IV?
They had been members of the previous union and had had the Constitution submitted to them for ratification by the previous union. That invitation to ratify the Constitution had not been withdrawn and there were no such conditions on their ratification.
The new United States government under the Constitution wanted as many of the 13 states to join it as possible. There is no way they would have been a practical country if the last four states of the 13 to ratify (New York, Virginia, North Carolina, and Rhode Island) had barriers making it more difficult for them to join. The ratification vote was very close in three of those last four states. It was 80-79 in Virginia, 30-27 in New York, and 34-32 in Rhode Island.
By the way, the 14th state (Vermont) also ratified the Constitution.
The fact still stands, as my post above shows, that prior to their ratification the US Congress considered North Carolina and Rhode Island not to be part of the United States, i.e., goods from those two states "... were imported or brought into the United States ..." How can that be if they never were outside of the United States?
After the collapse of British authority in 1775 it became necessary to form new state governments and by the end of 1777 ten new state constitutions had been created. Connecticut and Rhode Island kept their colonial charters but removed all references to British sovereignty. Massachusetts waited until 1780 to adopt it's new Constitution. All of this prior to adoption to the Articles of Confederation!
The were already free and independent states prior to their becoming party to any union whatever!
The Treaty of Paris acknowledged the 13 colonies to be free, sovereign, and independent states and that the British Crown and all heirs and successors relinquished claims to the Government, propriety, and territorial rights of the same, and every part thereof.