MagiDeal Bike Seat Post Quick Release Pin Binder Clamp Bolt Cycling Replacement Part Bicycle Alloy Seatpost

That pair of tabs sticking out from the frame, same color as the frame, below the black seat post, that’s an integrated seat post clamp and it needs a seat post clamp bolt like this https://a.co/d/0gTfRWc7 to secure the seat post to the bike.