When trying to install NBIS I get the following error on linux, when running ./setup.sh:

zsh: permission denied: ./setup.sh

and the following when running make config:

/bin/sh: 3: ./configure: Permission denied
/home/...../Downloads/Rel_5.0.0/buildutil/png_libs.mak:54: recipe for target 'config' failed
make[3]: *** [config] Error 1

I used ARK to extract the zip file.

What am I doing wrong?

Use the unzip utility to extract the .zip file containing the NBIS source. unzip maintains the file permission structure of the zip file contents. Then you can install as per normal.

Install guide

unzip nbis_v5_0_0.zip
cd Rel_5.0.0

sudo mkdir /usr/local/NBIS/Main
# Ensure a absolute path is provided to setup.sh
./setup.sh /usr/local/NBIS/Main --64 #or --32 if you have a 32 bit system
make config
make it
sudo make install LIBNBIS=yes

cd ..
rm -r -f Rel_5.0.0

I don't have access to the zip/can't use unzip

You can change the permissions of the relevant files with:

chmod ug+x ./setup.sh
chmod ug+x ./png/src/lib/png/configure
chmod ug+x ./png/src/lib/zlib/configure

Then you can install as per normal.