Which version and which OS?
Are you using Creative cloud app to download Photoshop CC? if no, download CC app via https://creative.adobe.com/products/creative-cloudand try to download.
If this doesn't work, please use the following direct download link: http://prodesigntools.com/adobe-cc-direct-download-links.html and choose Photoshop from the list.
Let us know if you were looking for some other version.