Hi Takahiro,

Welcome to Box Community!

Here are the troubleshooting steps to try:

• Updating your browser to the latest version


• Clearing your browser's cache


• Using Box with an alternate browser, computer, or network. If possible, Test using both Ethernet and Wi-Fi connections. Wi-Fi is typically slower than an Ethernet connection. Increased distance from your router can further decrease your speeds. If there are walls or other obstructions between you and your router, this could cause your internet speed to decrease. In that case, try moving closer to your WiFi router.


• Temporarily disabling any internet security/firewall programs to test whether they conflict with Box (Note: you may need clearance or assistance from your organization’s IT department/helpdesk to do this)


• Temporarily disabling any plugins/extensions in your browser


• Removing unwanted extensions, plug-ins, ads, pop-ups & malware:
  
  • 
    Chrome, Edge, Firefox, Safari
    
  
  

Reference: Common Issues with Downloading Files

Hope this helps and thanks for posting!

Thank you for your information!

I'm not sure what solved my problem, I could download materials from box.
Thank you again.