Hi @GloriaL , if you are not on Shopify Plus, you don’t have a direct access to checkout.liquid.
Go to settings > checkout and look for additional scripts, this is the place where you should add piece of code.
Please make sure that you have your checkout.liquid file enabled by the Shopify. Occasionally during theme copy the file might show up in your library, but it does not allow actually render anything if not being enabled.
Thank you so much for the answer. Yes, that’s exactly what happens.
We have reached out to the Elevar support, with their help to check, it turns out that our client copied the theme from the other site, so we did see a checkout.liquid but the functionality was not enabled.
After helping our client to enable the checkout functionality, everything works fine.