@soeungi, your colleague should be able to view the images from the server if and only if you make your data public as outlined in this community post discussed previously:
Please also be informed that you were able to view the images without any issue because you were logged into the server and you were opening the media files/attachments with the same browser where you logged in to your account. If your team had also logged into the account and tried to access the media/attachment then he/she should have also been able to view the image/media attachment without any issue.
