Strengths:
An interesting goal. Developing a completely new mechanistic time series model for a new application is a challenge in the duration of a final project. Nevertheless, the incompleteness of this submission does not do credit to the thought that went into designing the project.
Suggestions:
It is hard to comment constructively on an incomplete piece of work.
No need to show raw R output for the ACF and PACF
Page 5: A unit root is not usually described as a “stationary growth process” though one can guess what this means.
The requested source code file is not provided, though some of the code appears in the pdf.
References are missing.
Evidently, the authors ran out of time. It is okay if time limits the scope of the analysis, but that does not need to limit the level of scholarship.
More background on Twitch in general and the data in particular would have been useful to many readers.