https://wccftech.com/download-ios-15-beta-5-without-developer-account-right-now/

Here is how you can download and install iOS 15 / iPadOS 15 beta 5 without a developer account with Apple.

Apple has released the fifth developer beta of iOS 15 and iPadOS 15 just a while back and you can already get onboard the software release without spending a single dime. If you already have the previous beta installed then you can download the latest build by going to Settings > General > Software Update. However, if you are planning to download from scratch without spending a dime, then that option is available to you as well.