When I try to compile the tex file template I see this error What could the reason be? And how can I solve it?
The error says that a package used by the file is missing i.e. not installed yet on your TeX distribution.
TeXstudio ask you to download and install the package. In this case, I'll say you should install it.
You have to keep in mind that some TeX distribution (MikTeX for example), does not download all the package at the first install but do it when needed (which is the case here).