Concatenate multiple cells in one cell based on ID

I'm trying to figure out a formula for concatenating data in cells based on a condition. Specifically, I need to output rows for each unique "Conversation ID" (found in column C) and concatenate the messages (column D) in one of the cells in that row based on a unique identifier ("Conversation ID").

The messages are chronologically ordered (just for reference). The data that I would like to concatenate takes input from "Sender", "Conversation ID" (i.e. unique identifier), and message(s) and outputs that in the following form:

The google sheet is found here: https://docs.google.com/spreadsheets/d/1cza9uBiVuXSFqGRt-sQaVK76qfpdWnbxHGNe7_Dif80/edit?usp=sharing

Thank you,Martins