Assuming your ZeroSSL certificate is installed, it will work out of the box. If it’s not installed yet, this probably needs to be done through your hosting panel. Your hosting company can help you with that.
Hope this helps!
Thanks Rogier, it’s installed by I’m still getting the unsecure lock in my browser and it still lists the old LetsEncrypt as my cert 🙁 Maybe I need to reset something?
Turns out my hosting company updated their DNS, so I had to make this change for my domain, all fixed now, Thanks Rogier!