You'll find that ProBuilder is quite powerful once you get the hang of it. Creating curved surf ramps can be done the old-fashion Hammer method, or a simpler method of extruding and rotating faces. First we'll start with the Hammer method.
To begin, we want to rotate each segment of a ramp by a specific amount, so we'll set up rotation snapping to snap to every 5 degrees. To do this, Edit -> Grid and Snap Settings -> Increment Snap -> Rotation, set it to 5
Using the ProBuilder Window, create a Prism object with your desired dimensions. A good surf ramp dimension might be 16x10x4
Now duplicate the object using Ctrl + C -> Ctrl + V, press E to switch to the Rotation gizmo, hold Ctrl to enable rotation snapping, and rotate the segment in the direction you want it to go.
You can press W to go back to the translate gizmo. W, E, R, T are the hotkeys for switching gizmos, or you can click the gizmo button in the top left of the Unity Editor.
With the Translate gizmo selected, hold V to enable vertex snapping mode, hover over the bottom left vertex, and click/drag it to the first segment's bottom right vertex so they line up perfectly. Repeat this process until your curve is finished.
Now we will try out a new method using face extrusion and rotation.
Create a basic wedge like we did earlier.
Select ProBuilder's "Face Selection" tool, select the outer face of the segment, and click the + next to the Extrusion tool in the ProBuilder window.
In the dialog that pops up, switch Extrude By to Face Normal, and set the distance to your desired amount. The distance will be the size of each segment.
Close the Extrusion setting panel, press Ctrl + E to extrude the selected face. Note: You can also hold Shift and drag the translate gizmo to extrude the face manually.
Now with the newly extruded face selected, switch to the Rotation gizmo by pressing E, and while holding Ctrl to enable grid snapping, rotate the face in your desired direction.
After rotating the face, press Ctrl + E to extrude another segment, rotate that face, and repeat.
That concludes this tutorial. ProBuilder is very powerful, and I recommend you check out their documentation to learn all about it. Learning ProBuilder Hotkeys is very valuable for a productive workflow, and this guide introduces just a few of them. There are probably other ways to create ramps, don't be afraid to get creative and experiment!