Hi, @SalesBendella !
Julie here from Shopify Support.
Thanks for sharing the steps you’re trying to take in order to connect Shopify with Mailchimp. Because Shopify themes are structured quite differently than traditional websites, this is likely why you are receiving an error message when trying to add Mailchimp’s code to your theme. However, you can still integrate with Shopify using another method!
The easiest way to do so is by using a third-party app, since Mailchimp is no longer available in the Shopify App Store. This was a change that was made back in 2019 and you can read more about what this means for Shopify merchants here.
Both Shopify and Mailchimp recommend using an app called ShopSync. With ShopSync, you’ll be able to add a newsletter subscription popup to your website, or use Shopify’s existing newsletter subscription form if your theme offers one. Whenever a customer subscribes to your newsletter, they’ll be automatically added to your Mailchimp list.
Once ShopSync is installed, the integration process should be fairly straightforward. Mailchimp has some information on integrating with Shopify that you may find useful; as you scroll down, you’ll notice a section specifically for ShopSync. ShopSync also has their own setup guide that will walk you through the integration process and how their app works.
Just out of curiosity, how did you originally integrate your Shopify store with Mailchimp?