For testing just execute
CashierService.exe

to install it as windows service, run the following command once from administrator privileged command prompt CashierService.exe install

once the program is running you can call the following URLs

http://127.0.0.1:11501/cashier/ping just to test if the program is working

http://127.0.0.1:11501/cashier/open to open the drawer

CashierService.exe.config this is the configuration file, you can open it with notepad to change the default printer

you will need .net framework 4.6 to run this application