How to download an Overleaf template?

It's very easy, you open the document ("Open as template"), and click on "Project". Then you can either "Download as zip" or just open the file "wlscirep.cls" directly online to view in the Overleaf editor.

I would use the template from Overleaf (either downloaded or online), that way you should always get the current requirements.

"Download as zip" was not there in my case (2018/10/27) at project view. However, by going up a view: