There are a few ways you can apply a template to your server: during instance creation, manually on an existing instance, during Agent installation using the Manifest File, and as a default setting for instance groups. I'll detail each below.
You can manually apply a template to an instance by clicking the drop down and selecting "Apply Template".
A modal will open, allowing you to select which template you'd like to apply to the server.
Once you click Apply Template you can see the newly added checks on the server page with a template icon next to the checks.
You can bulk apply templates across multiple servers from the template page by going to the template page and clicking the drop down and selecting "Apply by Server".
A modal will open allowing you to select which servers and server groups you'd like to apply the template to. Selection of a server and clicking Apply Template will open a new modal confirming that you'd like like apply the template to the specified servers. Confirming by clicking Apply Template will apply the template to the servers selected.
As you can see from the image, you can also apply template by tag!
When adding an instance/server manually (not with the automated Agent method), one of the steps is to choose a template to apply to this new server.
If you choose to use this method, the checks, thresholds, alert timelines, and anything on the template will be applied to the server upon creation.
When using the Agent Manifest File during Agent installation, you can specify a template to use in the Manifest File. You can read more about the Manifest File in this article.
You can apply a default template to an instance group by selecting the group from the Instances tree in the left drawer.
Now that you're in the group page, you can edit the group to apply a default template. This way, any servers added to the group in the future will automatically have this template applied to them as well.