In RepU, open your widget and click Copy next to the embed snippet.
In your Wix dashboard, open Settings, then Custom Code, and click Add Custom Code. Paste your code, name it RepU, choose All pages, and select Body - end.
Click Apply, then open your live site to see your Google reviews.
Check your live site in a private window, not the Wix editor. A domain-locked widget only shows on your own domain.
Custom code needs a Premium plan and a connected domain. If you are on the free plan, upgrade and connect your domain, then check again.