I use XtrkCad v4.0.1, and I got an “examples” folder in the program folder (usually “C:\Program Files\XtrkCad” or something similar) when I installed it. Maybe there is a newer version out now that doesn’t include this folder, I don’t know…
I know of a couple of scenarios that generate error messages like yours:
When connecting two straight track pieces, and one of them (or both) are to short for the easement curve (which doesn’t show on the screen while you drag to adjust the radius). To resolve this, you have to lenghten the straight tracks before you connect them. If the track is to short because of a turnout in the other end, there is simply not enough room, and you have to remove the turnout and draw the curve first, then replace the turnout at the end of the easement curve.
Regarding minimum radius, there is nothing wrong with entering a minimum radius that is slightly smaller than the one you are going to use.
If easements are enabled, the radius set in the easement dialog box overrides your other minimum radius setting, you may have to adjust the easement settings a bit so that the easement radius is about the same (or slightly smaller) than your general minimum radius.
You can also, instead of connecting straight track sections, start with one track section and use the “Modify track” and “Split track” functions, something like this:
Split the track where you want the curve to start.
Select “Modify”, then SHIFT+drag to make the curve. Use the status bar to control the radius as you drag, release the mouse button when the radius is correct. Ignore the angle at this point.
Edit: If you choose “Describe track” and click on the curve just after SHIFT+dragging, you can enter an exact radius for that curve before you continue.
Then drag the curve into the desired angle. If you at the same time drag away from the curve you make a new straight section, an