You have 33 individual files from each manager across departments in csv format. Each file is identical in structure. Your final visualization of this data will include all 33 files. Which of the following seems like a logical first step to start your final data set?
Save all files into a single folder and use the data connection from Folder in Power BI that allows you to combine all the files.
Create a table in a database and then manually copy each file into the table. then connect to Power BI.
Import each file into Power BI individually then combine them one by one using append queries.
Copy each file manually into a new single file that contains all of them and then connect to PowerBI.