A very common way of sharing iOS builds is through TestFlight. Generally, these will be set up as shared accounts. This article goes through the process of how you access those shared accounts and some best practices as well.
1. When you are in a project the PM will most likely have added the TestFlight credentials to the project, which can be found by either:
a) Checking the Project Details
b) Checking the Cycle Details
2. When you are ready to test, you need to log into the TestFlight account on the iOS device that you have been assigned.
a) How to do this:
Go To Settings -> Tap on the first option to access your account settings -> “iTunes & App Store” -> “Apple ID: (existing email)” -> Sign Out
3. Download the build for testing, and complete your testing task
4. When finished, sign out.
a) Don’t redeem any codes on a shared account!
b) Don’t download any other apps on the shared account!