This is the link you need to download the program.
https://carlsondesign.com/hull-designer/It's a zip file that needs to be expanded. To do that, find the *.exe file that looks like this:
hulls32. Click on that and the Windows version you're probably running will extract the files and put them into a default location. Refind that
hull32 file and select it. Right click on it and select <Properties> then <Compatibility> Pick XP (or earlier). The program will now run.
Somewhere on the web there's a tutorial for how to use the program. But the best way to learn to use the program is to use it, all the while keeping this in mind. It's a old DOS program that's a bit buggy. The way to fix the bug is to relaunch the program.
There are other free mainrine CAD programs available. But none of them are as intuitive to use and none wil produce the cutting patterns you will need if you decide to build what you have drawn.