Duplicate Check for Dynamics 365 is available for download in the Microsoft AppSource. 

1. In AppSource, search for Duplicate Check for Dynamics 365 and select the app, or simply click this link.
   
2. Click Get it now. 
3. You are taken back to Dynamics where you can select your environment. 
4. In the Installation confirmation window, click Install.

Keep track of the installation process in the Solutions overview.

After installation completed, there are some configurations in Dynamics 365 needed before you can start using Duplicate Check. Please continue in Configure your Power apps for Duplicate Check‍.