Drag and drop the Twitter Archive zip file to Timehop. Now open a file explorer on your computer, and go to where the downloaded Twitter Archive zip file was saved. Click and hold the file. Drag it and drop it in the box in the Timehop page.
Alternatively, you can click the “Upload your tweets.zip archive” button inside the box, then browse for the download zipped file on your computer. Select the file and click “Open.”