(!) Please note: currency selectors and payment platforms (checkout) are 2 different things.
The app will convert prices in your storefront.
Want to add multiple currencies in your checkout as well?
We support multi currency checkout for merchants who use Shopify Payments >
https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency
If it's enabled in your store, then your clients could checkout with these supported currencies.
Follow these steps to set it up:
https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency/setup
This works automatically without any need to modify the app.
Anything not working as expected? we would be happy to help > Get help here