Even though you have an SSL certificate for your website, your visitors will not use HTTPS if HTTPS:// connection is not forced.
You can simply fix that by opening Hosting → Manage → SSL:
And clicking on Force HTTPS in front of the domain in question:
All certificates, installed via hPanel, force HTTPS by default
Before forcing HTTPS, make sure that your website works without issues (access it by adding https:// to URL). You might need to fix a mixed content first
If your certificate becomes invalid (expires) while you have a website forcing HTTPS, your website will be unavailable. No worries, Lifetime SSLs from Hostinger are active as long as you use our hosting 💪