Issues Installing Amazon_ES Plug In in Windows

Trying to plug in my IAM creds to get through an ES access policy in AWS, and getting an error that can't find the amazon_es plugin. So, there seems to be very little specific information on installing this plug in on Windows. I have gotten to the point where I downloaded the zip from https://github.com/awslabs/logstash-output-amazon_es, but uncertain on the exact syntax? Does it need to be placed in a specific directory? Seems like it shouldn't be extracted. The syntax on the little bit of documentation I did find was something like (from the logstash bin directory) run:

logstash-plugin install logstash-output-amazon_es-master

Have tried several variations like using the zip extension and having the zip in the bin directory or pointing to to it like C:\temp\logstash-output-amazon_es-master.zip or file:///c:/temp/logstash-output-amazon_es-master.zip and gives errors

Installing file: /c:/temp/logstash-output-amazon_es-master.zip

ERROR: Invalid pack for: file:///c:/temp/logstash-output-amazon_es-master.zip, reason: The pack must contains at least one plugin, message: The pack must contains at least one plugin

Just want to report that got it working by opening the CLI with elevated privileges, changing to the logstash bin directory and simply running:
logstash-plugin install logstash-output-amazon_es

One thing I am concerned about is storing IAM creds in a plaintext file. Has anyone found a more secure workaround? We are federating Kibana in general through an IDP in Cognito, so had to add the IAM user to the ES access policy for this to even work at all