Users can install this beta update on iPhone, ipad and iPod touch manually if they do not have a apple developer account. You just need to follow this tutorial. Download the respective file for your specified model and do the step by step method given in this article.
Download iOS 11 Beta 7 iPSW for iPhone/iPad/iPod
This is a Beta version so you should be aware that it is only meant for testing. You should make a full backup of your phone first before updating to iOS 11 Beta 7 so there should be a way for you to recover your device back if any issues occur with the update. See the instructions below to update your iphone, ipad or ipod touch to iOS 11 Beta 7 iPSW. Below are iOS 11 beta 7 download links. You can download the latest update for your specific phone model.
iPhone iOS 11 Beta 7 Download
iPhone 5s iPhone 6 iPhone 6 Plus iPhone 6S iPhone 6S Plus iPhone SE iPhone 7 iPhone 7 Plus
iPad iOS 11 Beta 7 Download
iPad Air iPad Mini 2 iPad Mini 3 iPad Mini 4 iPad Air 2 iPad 9.7-inch (2017) iPad Pro 9.7-inch iPad Pro 12.9-inch (1st generation) iPad Pro 12.9-inch (2nd generation) iPad Pro 10.5-inch
iPod Touch iOS 11 Beta 7 Download
iPod Touch 6