Are prices converted on the checkout pages?
Checkout pages are only managed by Shopify, apps are not allowed to modify them.
This is a Shopify intentional policy and no app can change that without breaking the Shopify 'terms and conditions' at https://help.shopify.com/en/api/app-store/listing-in-the-app-store/app-requirements#a-security
For that reason, prices will only be converted on checkout pages if you are using Shopify Payments Multi-Currency. See https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency/setup for details.
When Shopify Payments is configured in your store to sell in multiple currencies, Currency Converter Plus will integrate smoothly with it. You will be able to convert your prices to both currencies from Shopify Payments and extra currencies from Currency Converter Plus.
If you are not using Shopify Payments with Multi-Currency, our app will convert your prices on all public pages, including the home page, collection pages, product pages, corporate pages, and the shopping cart page but not during the checkout process, that will be performed using your store currency. A cart note can be configured to warn your customers about the currency change at checkout.