The Community Asset Bundles (CAB) are varied collections of 3D models, Unity asset bundles, and configurations for the HBS BattleTech 2018 game. They are a mod developers resource that provide no benefit on their own, and end-users have no reason to download or interact with them unless instructed to do so. Mod developers can use them to include new models into the game, if they understand how assets are loaded by the game.
Community Asset Bundle - Data contains references and configuration data for the installers that access the various CABs. End users and modders have no use for this repository.
If you have questions, join the RogueTech discord and ask for help in the #modding-and-model-making-questions.