Hello,
I'm really sorry if you feel so.
But as you can see this is not a simple process, but many things need to be done to achieve this. So I thing of redirecting to a good conversation where you can check the steps and determine what to do.
Moreover, your initial concern was only to get the header, so I have shared how to get that.
And, language school template description clearly states that it is not compatible with Joomla 5. Additionally, we have Joomla 5 tag also in the template list to short them. We expect our users will read them before purchase.
As customization support is prohibited here, and these tasks means customization, so I am just trying to pointing the tips hoping that these can help.
Best Regards