If you experience any difficulties when sending your photo, try to use another device, such as a computer or tablet. A smartphone is not suitable to compiling an application file which requires that you enter extensive information about your artistic work.
The problem may also be attributable to the quality of your Internet connection. In that case, try connecting to another Wi-Fi network.
Your internet browser may also be the problem, especially if your software is not up to date or if your settings were changed mistakenly. In this case, try using another internet browser.