c# – How Can I Add an Extensions to a Linux-based Azure App Service?

I am trying to follow the steps in this article to create a certificate for my website in Azure (link is to specific step):

www.virtusway.com/en/set-up-ssl-for-an-azure-web-application-using-lets-encrypt.html#lets-encrypt

When I get to the step in question, I do not see an “Extensions” link in my sidebar, nor do I see any way of adding Extensions. Upon googling, I see some vague references to Extensions not being supported for Linux apps.

Are Extensions not supported in my case, and (if so), why can’t I find any reference to that fact? Is there an alternative for Linux app services?