Run CocoaPods install for this project from the repo root:
pod install --repo-update
This installs all pods for the workspace (PrebidMobile.xcworkspace) covering all targets: core SDK, GAM event handlers, AdMob adapters, MAX adapters, demo apps, and internal test app.
After completion, remind the user to open PrebidMobile.xcworkspace (not the .xcodeproj) if they haven't already.