Enter the roller coaster construction page. We can make the roller coaster avoid the park terrain by raising the roller coaster and rotating direction.

Raising the level of the coaster until it floats above the terrain, building the coaster is no longer blocked

You can also rotate the direction of the roller coaster to place it in a suitable position

After successfully placing the roller coaster, since we are too high for the overall horizontal position of the roller coaster, we need to lower the road connecting the entrance and exit to the main road.

If you still cannot place the roller coaster normally, you can open the game settings and select [Disable Roller Coaster Collision] in the game menu to allow the roller coaster to be placed through the existing terrain.
