"You must make chain_reactor first"

[ghost]

Hi
I'm using a straight out of the box Ubuntu build and I get the following when trying to build the illustrative example:

:/code/chain-reactor$ python3 compose_reaction atoms.json reaction.json ./example
Traceback (most recent call last):
File "compose_reaction", line 70, in
assert os.path.exists(os.path.join(script_directory, 'build/_X86_64/chain_reactor')), "You must make chain_reactor first"
AssertionError: You must make chain_reactor first

$ uname -mrs
Linux 5.8.0-55-generic x86_64

$ cat /etc/issue.net
Ubuntu 20.04.2 LTS

$ python3 --version
Python 3.8.5