Out of Downloads?
Once you open your order pay attention to the download icon next to your design's thumbnail (in the LH panel). You may have a restricted number of downloads for your designs. If you do it will be indicated with a number next to the icon. If there is no number then your design has unlimited downloads
In the example above, the "Banner Vertical" design has 1 download left. Once you use that download the number will tick down to 0 and you will not be able to download the design anymore. If you try to download you will receive a pop up notification telling you that you have no downloads left. If you need additional downloads you will need to reach out to the seller you purchased from to request additional downloads. Since each seller has different download guidelines we cannot add any additional downloads for you.