Had downloaded the free version of the train track years ago but found it personally useless here.
When running virus program recently it also quarantened it on my old mac.
Also have tried published designs to learn from but honestly believe some had never been built before printing.
So best advice can give is to just do it and see how design works out.
It helps to take notes and use a ruler to check parallel lines and a calculator to do the math if unable to handle the non standard designs.
There are numorous sites that give the diminsions of the curves and straights.
You will need short straights, at least 4 to make anything minorly creative and the scaly digital systems will also require certain track design requirements to function properly.
Believe scaly should make single lane shorts with the same connector as the singe straights.
Any serious discussion of track design would become complicated and long here.
So my best advice to learn track building remains just do it.