I don’t think anybody addressed this topic, so I’ll try to help you out…
When you see stuff about 2.5D, what people mean is “roughly” 3D. In most of the forums about hobby CNC, “2.5D” and “3D” are interchangeable. For example, this is a “3D” fish puzzle I carved on my Shapeoko
Generally speaking, 2D carving is cutting away material such that all the surfaces, are perpendicular to the router axis, just at different heights. Your signs are 2D machining. 2.5D means using a ball mill and the machine moves in the X & Y directions, synchronizing the movement of the router in the Z direction to give you a smooth shape, like with the fish above. True 3D would involve turning the material so that different faces are presented to the endmill. The Shapeoko can’t do that as it is (although people have done it by doing one side, turning the material 90 degrees, doing the second side, turning again, etc. Check out this post by @RichCournoyer. The man is a freaking wizard) Doing it automatically would involve doing some work with different controller boards, etc. This link may explain 2D/2.5D/3D better than I can https://www.flashcutcnc.com/node/82
Carbide Create and Vectric V-Carve will only do 2D designs. You can do some fancy 2D designs though with various endmills; v-bits will give you sloped edges, ball mills will give you rounded edges on pocket bottoms, roundover bits will give you rounded edges on outside edges.
Fusion360 and Vectric Aspire will do 2.5D. Aspire is what I used for the fish above.
Fusion360 will also do 3D, if you have a machine capable of doing that, what they call a 4-axis and 5-axis machines. The Shapeoko is a 3 axis machine.
As for “is it ready to go right out of the box?”. No. However, I got mine a year ago, put it together after following all the helpful assembly docs and after reading everything on this forum that I could find about tips and tricks, and it worked the first time. Most of the issue people have is from skipping a step during assembly, not understanding how things work in general, or trying to run before they learn to walk. It’s like with the turnings you do… you did not start off turning those gorgeous objects right off the bat, one would assume. If you’re like me, I spent forever just setting up the lathe, then a half an hour making sure the block was perfectly centered in spindles before I even turned it on. The first time I put chisel to wood, I was scared as heck and had no idea what would happen. I didn’t jam a gouge into a spinning block of wood and hope for the best.