You have the option to deliver difference sizes via Pixieset (this is customized under Download Settings in your dashboard). Web Size files are 1024px on the width and it's meant for social sharing. High res files are optimized for faster delivery time while keeping the quality high at 3600px. If you wish to deliver the Original files exactly as you uploaded them, you can choose the Original option under Download sizes.
We often see clients unable to download files because the files are too big, or the internet connection gets disrupted, we recommend High res because it's more optimized for this process. However depending on your workflow, you can definitely go with the Original if you choose to.
Here is more information and also where you can change the settings: