In RepU, open your widget and click Copy next to the embed snippet.
In Square Dashboard, go to Channels, then Square Online. Open Settings, then Tracking Tools, and click Add new code. Paste your code, name it RepU, choose End of body, and click Save.
In the site editor, click Publish, then open your live site to see your Google reviews.
Check your live site in a private window, not the Square Online site editor. A domain-locked widget only shows on your own domain, not your square.site address.
Custom code needs a Plus or Premium plan. If you are on the free plan, upgrade, then check again.