Please visit the github page for information:
Umbraco.Elasticsearch is an Umbraco plugin designed to integrate your CMS with Elasticsearch. It is not designed to replace any built-in search features of Umbraco (Examine) and instead provides an independent point of search integration in which your CMS acts as a data source for your search index.
Install Umbraco.Elasticsearch via NuGet: Install-Package Umbraco.Elasticsearch
Umbraco.Elasticsearch is not an "install and forget" solution, to use it you will be expected to have knowledge of the following:
Installing Umbraco.Elasticsearch does not instantly give you full-text search over your CMS content, you will need to review the sample projects or read the documentation to learn how to get up and running.
Information on the latest release can be found within the github releases.