Both (overall site and the subsite) are in Kentico.
I know that it is possible, but to do so you need IIS which is not available when deploying on an Azure server.
See this documentation:
Setting up multiple sites on a single domain
We have tried this:
general site 'example' has domainname
and subsite 'campagne1' has domainname
So my question remains: How to configure a subsite in Kentico on a Azure server on one domain?