I have installed the search engine and made an index of my domain. But when I use the search-demo.html and try to search, a "Method Not Allowed" or "The requested method POST is not allowed for the url /index.htm" error message appears instead of search results.

Alkaline is a full web server and does not need your current web server such as IIS or Apache to function. Alkaline requests must reach Alkaline. For that purpose, Alkaline is running on a specific port. Your default web server runs on port 80. Running asearch 9999 Alkaline will bind it to port 9999.

Your template is posting to a wrong port, certainly the default one (80). Make sure to modify the template search form accordingly to the value you specify when launching Alkaline, for example:

<form action="http://www.server.com:9999/test/test.html" method="post">

with Alkaline running on port 9999.

Use high port values as low ones are often reserved for certified protocols. Proxies might filter and block strange port values, 8080 is often a good choice.