Well, I don't own Poser so I can't test it out for you, but it seems like it's fine. Did you do everything correctly according to the freebie uploading instructions at the top of the upload page?

Requirements Thumbnails must be 300x350px. Supported formats include .jpg, .png, .gif. Promo Images require a minimum width of 800px or maximum width of 1200px, if not within range images will be proportionally scaled. Supported formats include .jpg, .png, .gif. File size is limited to 200 MB File format should be in .zip Proper category placement by provider is required. Items not in proper categories may have a delayed/declined release. If you are unsure of the category, please contact any Freestuff staff member for assistance before uploading.