How is Audio Identification transcription text created from JSON?

Dislaimer: I'm not a CS major :(

My son records lectures (1-5 people) in college. With AWS Transcribe, I've upload an audio file (in buckets), and transcribed it.

The transcription ("asrOutput.json") is a file he can open in Notepad, copy to Word, and format (id speakers, adding paragraph breaks, etc.).
However, I found that "Speaker Partitioning" breaks the long body of text into various speakers, making the output/reformatting much easier for him (http://threadgill.com/TranscriptionPreview.jpg).
But how do you have AWS built-in Lambda do that?
This question was asked in 2018 (https://github.com/trhr/aws-transcribe-transcript), but the answer's step-by-step instructions weren't applicable in today's UI for Amazon S3 > Buckets, or Amazon Transcribe > Transcription.
Per the answer, S3 has a Lambda function that triggers when uploading arsOutput.json into an "input/" folder, creating a Speaker Partioned formatted file in the "output/" folder.
Per the github instructions, I created an S3 bucket with two folders: input/ and output/ , but was unable to properly configure the Lambda function.
Any help would be much appreciated!