In RepU, open your widget, choose light or dark and left or right, then click Copy next to the embed snippet.
In Shift4Shop, go to Content, then Header and Footer. Turn off the WYSIWYG editor, paste your code into Global Footer, and make sure the section is enabled.
Need more detail? See the official Shift4Shop guide.
Click Save, then open your live store to see your Google reviews.
Check your live site in a private window, not the editor or preview. A domain-locked widget only shows on your own domain.
Make sure the WYSIWYG editor was off when you pasted, and that the Global Footer section is enabled.