Follow these steps to get your diary.csv file
Head to letterboxd.com and sign in to your account.

Click your avatar in the top-right corner and choose Settings — this opens your Account settings.

In the settings tabs, open the Data tab.

Click “Export your data”.

Your data downloads straight away as a .zip file — no email needed.
Unzip the downloaded file. You’ll find several CSV files inside.
Find the file named diary.csv in the extracted folder and upload it on the home page.