You can find out those Shopify free themes here:
Please follow step by step to install star ratings on your collection page.
From your Shopify admin, Sale channels > Online Store > Themes > Edit codes
Find card-product.liquid or product-card.liquid file in Snippets folder
Find this line of code :
{% render 'price', product: card_product, price_class: '', show_compare_at_price: true %}Copy and paste Ryviu star rating code below before the line of code I mentioned in step 4 above.
<!-- RYVIU APP :: COLLECTION-WIDGET-TOTAL -->
<div class="ryviu-collection"><ryviu-widget-total collection=1 product_id="{{card_product.id}}" handle="{{card_product.handle}}" reviews_data="{{card_product.metafields.ryviu.product_reviews_info | escape }}" ></ryviu-widget-total></div>
<!-- RYVIU APP -->
If the code above does not work, please use this one.
<!-- RYVIU APP :: COLLECTION-WIDGET-TOTAL -->
<div class="ryviu-collection"><ryviu-widget-total collection="1" reviews_data="{{product_card_product.metafields.ryviu.product_reviews_info | escape }}" product_id="{{product_card_product.id}}" handle="{{product_card_product.handle}}"></ryviu-widget-total></div>
<!-- RYVIU APP -->Click Save button, and you are done.
If you need more assistance, please feel free to contact us.