If you're seeing the following screen, that means that your browser is loading your audio file in a separate tab.
This is unrelated to Trint.
There are two reasons you might be seeing this screen when trying to upload:
1. You are trying to upload from the wrong screen. If so, please follow the instructions here: https://support.trint.com/en/articles/3004399-how-do-i-upload-my-file
2. You are trying to drag and drop twice in a row. Instead, you will need to drag all of the files into the upload screen at the same time, or select them manually.