One of the simplest ways to install NGLess is through bioconda:
conda install -c bioconda ngless
You can get a statically linked version of NGless 0.5 or a nighly build of the latest development code. This should work across a wide range of Linux versions (please report any issues you encounter):
curl -O http://ngless.embl.de/releases/ngless-0.5.1-Linux64 chmod +x ngless-0.5.1-Linux64 ./ngless-0.5.1-Linux64
This download bundles bwa, samtools and megahit (also statically linked).
If you want to try one of ngless’ builtin modules (motus, specI, ...) you can download the full nighly build zip file which includes them.