These are predicted like any other dimension, and when this flows into your ERP, the splits defined by your Allocation will take place there. Note, not all integrations support Allocation functionality.
Like any other data point, the AI will learn over time what allocation should be used in which situation.
Please note, while generally selecting an Allocation mean no other Dimensions are used, some businesses use Dimensions in conjunction with Allocations. Make sure to cultivate the AI by using the correct combination for your company!