Mistakes:
1. Wrong boundary condition. Your transformer in Momentum is placed at 10µm distance above a solid ground plane (bottom cover in Momentum substrate). This metal plane under the inductor dramatically changes inductor magnetic fields, this can't work. There is no such ground plane in your reference paper.
Solution: Remove the ground plane. You can use differential ports with explicit (-) pins to place the port reference. The (-) pins then go to the one end of the spiral that is connected to the ground via at the moment.
2. Your inductor is inserted into the conducting silicon with no isolation between metal and silicon substrate. This is wrong, and different from the model in your reference paper.
As I mentioned in your other post, in Momentum you can't model this very special case where the inductor inserted into the silicon substrate with a thin isolating oxide layer as isolation. That requires 3D volume meshing (FEM solver) and can't be done with the Momentum solver. Also, it is tricky to create the isolating oxide. That setup will take hours even if you are an ADS expert.