You are right. The Invoke-VMScript cmdlet only runs on PowerCLI 32-bits. If you have installed PowerCLI on a 64-bits system, you will have the "VMware vSphere PowerCLI (32-bit)" also installed on your system. You should use that to run your script.
If you have any problems with the script itself, let us know and we will try to help you with the script also.
Regards, Robert
Blog: https://rvdnieuwendijk.com/ | Twitter: @rvdnieuwendijk | Author of: https://www.packtpub.com/virtualization-and-cloud/learning-powercli-second-edition