If you try selecting a palette and clicking "PBNify" and it doesn't start computing, then there could be a compatibility issue with your device or browser. Try running it from a different computer.
Usually it finishes within a minute, but it could take longer depending on the computer speed, having a lot of colors chosen for the palette, or having a very tall image. Hopefully changing one or more of those will get it to finish.
I do not have an installable version since it's written in web languages and would require substantial rewriting. However, since everything happens locally in the browser, you could in theory run PBNify offline. You'd have to download the repository, replace CDN references to local libraries, and run a local web server to serve PBNify from that directory.
PBNify always resizes the input and output images to a width of 800 pixels. However, if the image is wider than it is tall, you could rotate it beforehand. Then, the smaller dimension will be set to 800px, and would allow for more detail.
Those are different ways of specifying a color as used with computers and printers. The hex code (e.g. #386e97) and RGB give red/green/blue components, HSL gives hue/saturation/lightness, HSV/HSB gives hue/saturation/value(brightness), and CMYK gives cyan/magenta/yellow/black, which is used for printers. I included all of them in case they are helpful in obtaining paints for the palette colors, but I'm not sure which ones are actually used for that, if any. When I've done PBNs I've only mixed basic paints to approximate the colors. If you find out what color specifications are used to buy custom paint colors, let me know and I'll add it!
PBNify cannot provide a vector graphic because its algorithms are based on a pixel grid and directly create a raster image.
This step can vary because different devices and browsers handle it differently. One option is to "print to PDF" from the print page, which saves it as a PDF file. Otherwise, you should be able to close the print box, right-click on the image and save it. As a last resort you can screenshot and crop. You can do that from the main page if the tab that opens is blank.
You are welcome to use, copy, and modify the code, including for commercial purposes. I don't have time to help with business ventures, but I'd love to see what you do with it.
You may also use the PBNify output you create for commercial purposes, such as in a coloring book, as long as you aren't infringing copyright on the source images.