Last step: Redirect http to https on subdomain

Hi Ron,
I have followed all settings as explained and it is just perfect as i would expect it.
My main domain is viagemcultural.com. my subdomain is kiddos.viagemcultural.com and the primary site is now lingolink.org with the following URL:

https://lingolink.org

The problem and i hope this is the last is that http://lingolink.org does not redirect to https.
How can i make it happen.
It seems that it works with my main domain.

Thank you,
Fabrice Theveny