While Motion Bro 4 is the current standard, many editors stick with 3.2.1 because:
The classic interface is preferred by some long-time users. How to Download and Install Motion Bro 3.2.1 motion bro 321 download work
If you are looking for a that actually works, you’ve likely encountered the frustrating "Unable to run script" error or a blank panel in After Effects. Version 3.2.1 was a pivotal update for the popular preset manager, but because the software has since moved to version 4.0+, many users struggle to get the legacy version running on modern systems. While Motion Bro 4 is the current standard,
Troubleshooting Motion Bro: How to Get Version 3.2.1 Working motion bro 321 download work
Older .list and .mbr preset packs are sometimes more stable on the v3 architecture.