Hello Sreevishakh
I would recommend starting with the Getting Started with the KW45B41Z Evaluation Kit | NXP Semiconductors instructions.
Download the latest SDK version [25.06] from the MCUXpresso SDK Builder
The Interface to test the SDK examples is the MCUXpresso IDE tool [latest version 25.06] as described in the getting started guide, then you can test any SDK examples with the KW45 EVK board.
Please refer to the following link for more detailed instructions Run a demo using MCUXpresso IDE — MCUXpresso SDK Documentation
If you want to start testing some applications related to Wireless and Bluetooth please to refer to the Bluetooth Low Energy Demo Applications User’s Guide , this guide describes the hardware and toolchain requirements and steps to build and run the demo applications examples included in the software development kit. The examples are located in the SDK Wireless_examples->bluetooth folder
If you need some other information as Application notes, User Manuals, datasheets etc please refer to KW45B41Z-EVK Main page Documentation section.
For testing any custom application, I would strongly recommend you take an existing example from the SDK as a base and then apply the modifications to your custom requirements; The Interface for flashing is the same MCUXpresso Tool.
The Source code for NXP IoT Toolbox app is not available for download or review.
Best Regards
Luis