To use DaVinci Resolve templates, you need to open them up in the DaVinci Resolve software. The best way to do that is through the Project Manager.
Open up the DaVinci Resolve Project Manager, and then right-click anywhere, and select Restore Project Archive.
Navigate to your template folder and click Open.
Your project should now be available inside the Project Manager. Double-click it to open up the project.
NOTE: Please make sure to have the custom font that the template was made with prior to opening the project for the best experience.