Please refer the way below to take reviews back:
Step 1: Go to your Ryviu dashboard > Settings, click Add snippet codes button. Our app will add Ryviu snippet codes to your Template/product.liquid and Sections/product-template.liquid by default.
Step 2: Add stars rating under product title for your collection page:
Please follow this instruction: Stars rating for collection page
If you need some more help, please feel free to contact us via our live chat widget.