Gitlab pages "Your connection is not private"

I setup a domain and verified it on Gitlab pages. I checked the Lets Encrypt certificate on on Gitlab so I can use that but everytime I go on my website, it says " Your connection is not private" and the certificate that shows is Alpha SSL CA. I’m not sure if the Alpha SSL CA is causing the " Your connection is not private" problem or if it’s something else. How can I make the Lets Encrypt certifticate show up on my website I’ve been waiting about 2 days now and it’s still not up.