Hi Mark_1503,
Thank you for posting in Apple Support Communities! Sounds like you're using Quick Start to transfer data to your new iPhone, is that right? Have both devices been restarted? To restart, press and hold either volume button and the side button until the power off slider appears. Drag the slider and wait about 30 seconds. Press and hold the side button until the Apple logo appears to power it back on. Once back on, try to transfer data once again.
Restart your iPhone - Apple Support
If this continues, you'll want to confirm both devices are up to date by going to Settings > General > About > Software Version. The latest iOS for both devices is iOS 15.4.1. You may need to set up the iPhone 13 Pro Max as new, update, erase it and then attempt to use Quick Start again.
Update your iPhone, iPad, or iPod touch - Apple Support
To erase the device when ready, you can go to Settings > General > Transfer or Reset iPhone > Erase All Content and Settings.
Erase iPhone - Apple Support
Hope that helps!