Just simply run:
sudo apt install nwchem
it's a supported package which already exist in official repository, and the link you provide is the source of it.
The fact is that you already have access to the source of this package, if you want to download the source you can run:
apt source --download-only nwchem
And if you want to compile and install it from source code:
first install the built dependencies.
sudo apt build-dep nwchem
then use this command to fetch and compile nwchem
apt source --compile nwchem
then install it:
sudo dpkg -i nwchem-version.deb
or you can use things like gdebi to handle dependencies too.