Unable to find the development tool `cc`

In a standard 20.04 system, cc is usually a symlink handled by the alternatives system to the GNU C compiler (gcc):

$ ls $(which cc) -al
lrwxrwxrwx 1 root root 20 Nov 21  2018 /usr/bin/cc -> /etc/alternatives/cc

$ ls /etc/alternatives/cc -al
lrwxrwxrwx 1 root root 12 Nov 21  2018 /etc/alternatives/cc -> /usr/bin/gcc

You probably don't have build-essential installed, and NVIDIA needs the compiler bits to actually install and handle the driver. Run sudo apt install build-essential and install the GCC compiler and such via that package. Then run the .run file from nVidia again.