Make sure you have downloaded the latest version of the software.
Unzip the File that you have downloaded.
In that ZIP File you find two files.

You also need to download and install Java.
I personally recommend JDK 15-.0.2 and you can find that here.
You can also download a newer version, but if things aren't working as expected then remove all Java and install version 15-0.2

In Windows Click with the Right mouse button on the Windows icon (The Start button) and choose Run
Type cmd in the Run window and click on the OK button
A new window will pop-up.
Type the following in this window. java -version and press on the Enter key.
At this point there are two possible outcomes.

1. 'java' is not recognized as an internal or external command, operable program or batch file.
2. Java version "VERSION NUMBER" and some extra info about the current version.

In case 1 The java is not recognized error install the jdk-15.0.2_windows-x64_bin.exe this will install Java version 15.0.2 The software is build on this version of java. so it should work perfectly.

In case 2 which means you already have Java installed.
I recommend to update to version 15.0.2 if the version you are running is lower than 15.0.0.
if you are running a higher version than 15.0.2 my advice is to try to run the software. if there are any problems, remove the current Java version and install version 15.0.2

If you have Java version 15.0.2 installed you can start the program just by double clicking on the Receipt-Printer.jar

you can also double click on the StartPrinter.bat file, this will open an extra window that shows what happens behind the scenes and can give some information when things go wrong.

In some cases if your java version is above the recommended one the program will only start with the StartPrinter.bat file.