1. When you tick "Please check this to add additional files," the next step is to click "Submit."
2. Then, it will take you to the next page, where you can upload your supplementary/individual files. Your files windows will pop-up. Just click "Save," every time you finish uploading a file.
When you have finished uploading all your supplementary files, just click "Continue."
IMPORTANT NOTE
Click "Continue" only when you have finished uploading ALL individual files because clicking "Continue" will finish the submission process.
For more help, you may also refer to Animo Repository How To Guide