Not sure what your particular problem is, but we have a guide about SSL on Shopify, maybe it can be helpful?
Finley from Shopify here!
Adding a custom domain is an important step for your business, as it will reinforce your brand and give your website a professional look. Thanks for posting this question!
If so, after properly adding your third-party domain to the Shopify admin, your SSL certificate is automatically created. It can take up to 48 hours for the SSL to move from the pending status.
However, because it's been longer than 48 hours, you may be having issues due to the domain's DNS records being incorrect. If this is the case, then these DNS records would need to be updated.
Connecting a domain
When connecting a domain to Shopify, you first need to reach out to your third-party domain provider so they can help you update your DNS records. Alternatively, you may be able to do this yourself, following their instructions.
The DNS records required to connect a domain to Shopify are:
1) An A record which points to: 126.96.36.199
2) A CNAME record that points to: shops.myshopify.com
Note: Something that could get in the way of your domain connecting is also having multiple or old A records or CNAME records. Be sure to only have Shopify's and remove any previously added A or CNAME records in your domain provider's account.
If you need further assistance with your third-party domain, please reach out to your domain's support team for assistance. Because this is external to Shopify, our team has limited visibility and won't be able to log into your domain provider's account for you.
The next steps for your domain
After completing the steps above, your domain will be ready to connect in the Shopify Admin.
You can navigate to your Shopify Admin > Online Store > Domain > Connect existing domain and enter in your custom domain:
Following this, you can set your custom domain as your primary domain so that your customers will always see this URL when they visit your website.
I've gone ahead and sent you an email to your Shopify Community email address, in case you require further assistance on Shopify's side of things. Feel free to reply to that email with your .myshopify.com URL if you'd like me to look into the specifics of your account.
The next steps for your website
How are things going with the rest of your website? If you're still in the initial set-up stage, we have a wonderful step-by-step guide with your next action steps, such as:
I hope this helps and as always, please reach out if you have any questions!