If your file is too big to upload, then you should do the following: 

Option 1: Follow this link: https://shortpixel.com/online-image-compression  where you can upload your file and make it smaller

Option 2: Follow this link: https://online2pdf.com/de/  there you can generate a pdf from your file and upload it during the verification. 

If you still have problems, our support team will be happy to help you.