If you haven't done so already, create a Stripe account.
Back at Gridbox editor, drag and drop Stripe component into the canvas.
Edit the button text if you want to. (Optional - Click on the button and click on </> icon from the blue highlighted toolbar -> change the text and save)
Click on the button, then open the properties panel, enter the following information (API Key, Price ID)
Success URL, which can be any valid URL or blank to use the site's current URL.
Cancel URL, which can be any valid URL or blank to use the site's current URL.