The short answer is BLM did not need state approval for this purchase of land because it was not land owned by the state but private property and purchased only for recreational use.
If you are interested, below is a more detailed explanation:
The Constitutional provision you referenced is Article I, Section 8, Clause 17. This clause says that Congress can exercise authority over all places purchased by the federal government within a state, with the consent of the state’s Legislature, for the erection of forts, magazines, arsenals, dock-yards and other buildings. That doesn’t apply here because the BLM purchased the land for outdoor recreation, not a military installation or similar property over which the federal government could claim exclusive jurisdiction. (This question of jurisdiction can get very complicated, but just remember that the federal government’s jurisdiction is exclusive in areas like Hill Air Force Base, not places like a bike trail.)
So in this case, the BLM also didn’t need the Legislature’s approval to meet Constitutional requirements before it executed the sale since the federal government isn’t seeking to control the area as described in Article I, Section 8, Clause 17.
To answer your question about how the legislature gives approval for the purchase of state land by the federal government, the process is found in the state code section 63L-2-101. However, in this case this statue does not apply because it was not state land being sold or exchanged but it is private property.
Hope that helps, feel free to reach out with any other questions or concerns.
Senator Ralph Okerlund