ZXPSignCmd not executable

I don't know where else to ask this question but I'm following the guide for creating an extension from this link: https://github.com/Adobe-CEP/Getting-Started-guides/tree/master/Package%20Distribute%20Install

It says to download ZXPSignCmd from the git repo and install the .dmg. I'm using the 4.1.2 folder on MacOs. The other folders don't seem to have working MacOs downloads. This one downloads and runs and something executes because I get a message like this: 

/Volumes/ZXPSignCmd-64bit/ZXPSignCmd-64bit ; exit;

Usage:

    ZXPSignCmd -sign <inputDirectory> <outputZxp> <p12> <p12Password> [options]

options:

-tsa <timestampURL> - will attempt to timestamp the ZXP using supplied timestamp server. For example, https://timestamp.geotrust.com/tsa

    ZXPSignCmd -sign <inputDirectory> <outputZxp> -s <identity> [options]

options:

-keychain <filename> - identity is only looked-for in the specific keychain given

-tsa <timestampURL> - will attempt to timestamp the ZXP using supplied timestamp server. For example, https://timestamp.geotrust.com/tsa

    ZXPSignCmd -verify <zxp>|<extensionRootDirectory> [options]

options:

-certInfo - will print out information about certificates (including timestamp and certificate revocation information)

-skipOnlineRevocationChecks - will skip online checks for certificate revocation (certificate revocation checks only happen with -certInfo flag set)

-addCerts <certificate1> <certificate2>... - will verify certificate chain and assess whether or not DER encoded certificates passed in are included

    ZXPSignCmd -selfSignedCert <countryCode> <stateOrProvince> <organization> <commonName> <password> <outputPath.p12> [options]

options:

-locality <locality> -orgUnit <orgUnit> -email <email> -validityDays <validityDays> - are optional attributes for self-signed p12 certificates

logout

Saving session...

...copying shared history...

...saving history...truncating history files...

...completed.

--

but now what? the command doesn't run and the terminal says command not found. I've tried changing directories and changing permissions. Am I missing something? There is no 

ZXPSignCmd file on my machine, I have searched. The closest is 

ZXPSignCmd-64bit but that's doesn't run as a command either in terminal. I am new to this so maybe I'm missing something obvious. Can anyone help?