The Samsung Galaxy Note 4 on T-Mobile is now receiving the android 5.0.1 Lollipop update. The update is 1.1GB in size and bring a Merial Design inspired user interface, the 64-bit ART compiler which will help apps open faster, Project Volta for improved battery life, and Lock Screen notifications. The update also offers a new "Recent Apps" multitasking interface, easier access to Quick Settings and the Smart Lock which unlocks your phone automatically when it is paired to a device running Android Wear.
The update is being pushed out OTA and in stages, so it maybe a few days before it is available for your device. You can try manually checking for the update under Settings.
Because of the larger size of the update, users are advised to connect to Wi-Fi before downloading it. It is also recommended that you ensure your battery its appropriately (at least 50%) charged before you install the update. The entire process will probably take you more than 20 minutes to complete.
source - AndroidAuthority