Downloading the Project : you can download the zip file and then unzip it , and open it with unity. It would take sometimes to restore the library folder so you need to wait. after that you can look for sample scene in the project and double click it.
You can use the build zip and unzipt it to upload the game on some website.
To try the game right away click this link : https://young-gamedev.itch.io/shelf
How to play : you can refresh products , and you can click the product and come closer to modify the name and the price , the product is saved and if in the future you would get it again when you refresh the previous changes would appear because they are saved