Transparency Product Enrollment: Error message saying file not supported.

I'm trying to enroll a new product on Transparency.

Step One: Download file

Step Two: Fill out necessary fields on the form

Step Three: Upload file

I am getting an error message saying that the file is not supported. The downloaded file was an .xlxm file. I have tried uploading .xlxm and .xlxs and .cvs and none of them are being accepted. Now, I don't have Microsoft on my Mac. I use Google sheets and download the completed form. I don't know what the issue is, nor does the page say what the supported file should be. I emailed Transparency through their contact form over a week ago and they have not responded.

Anyone has any suggestions?