This is not correct:
Netlify will allow you to use your own SSL certificate or you can have us provision SSL for you using Let’s Encrypt. We do not require you to use a third-party SSL certificate but you are free to do so if you want to do so. We at Netlify do not care either way. You are free to do whatever you prefer and we do not attempt to control this decision in any way.
I looked up the real domain and site. The DNS for your domain is misconfigured and you have an inactive Netlify DNS zone. It should be deleted and there is a support guide with an explanation why here:
The solution here will be the following steps:
- delete the inactive DNS zone at Netlify
- delete the NS records for the Netlify DNS zone from your registrar’s DNS service
- add the DNS records at your registrar following the instructions here: Configure external DNS for a custom domain | Netlify Docs
- Once the DNS records from step 3 exist, click the “Verify DNS configuration” button in the site’s “Domain management” page at Netlify
Step 4 above should start the Let’s Encrypt SSL certificate provisioning process. If it does not, please let us know.