Gotcha, thanks for confirming. As mentioned, because Shopify will automatically provide an SSL certificate from our end when a store connects their third-party domain to a store, you won’t be able to transfer or connect your own SSL certificate from another provider to Shopify.
From here, if you haven’t already connected your domain to your Shopify store, then as previously explained please follow the instructions in this guide in order to manually connect your third-party domain to your store.
Just a note that because your domain is hosted by a third-party provider, if you have any issues or need assistance with updating your domain’s DNS settings to point to Shopify, you’ll need to get in touch with your domain provider’s support team directly as they’re best equipped to help you.