Fort Sumter was a fort, a military institution. It was not used as a tariff collection point prior to the time Major Anderson moved his command there and it wasn't used as such afterwards. The Customs House was (and still is) on East Bay Street. Just another DiLorenzo whopper.
Actually, in a March 18th cabinet meeting discussing what to do about Sumter, Lincoln specifically brought up and addressed the question of whether to use Sumter as a tariff collection point, or to transfer that role to ships outside the harbor.
Notes from the meeting specifically mention the question being asked "Is [Sumter] available under existing circumstances for the purpose of collecting the revenue" or could that role be "better subserved by Ships of War, outside the harbor."
In other words, DiLorenzo is correct about one of Sumter's intended roles by Lincoln being tariff collection. You are the one lying.