Fastest way to learn flutter app architecture like MVC, MVVM , etc

i started a job for a startup company and they had some project running but without any separation for business logic from UI and no app architecture or design pattern used to build them, you can imagine the performance of the apps :/ . I am on a tight schedule to build a multi-restaurant app in one and a half month but i have no knowledge with any of the MVC or MVVM pattern . tried Blocs but it was complicated and found it hard to grasp quickly. Please guide me on how to separate my files for the project ? how to structure my app files, is it by feature or there is a common way to divide the folders of my app ? Thanks.