The relationship between carrier, US Customs board of Protection and US Customs Broker
In order to get the pre-cleared message ( AKA:1C) of imported cargo from the customs board of protection, it is not just bilateral interaction between the customs broker and CBP. It is a result of a tripartite mechanism. The following diagram can roughly represent their inner relationship

If non-consoldiated air cargo, the carrier needs to submit AMS
of cargo on board and FDM( Flight departure Message).
If non-consoldiated ocean cargo, the carrier needs to
submit e-manifest and VDM (Vessel Departure Message)
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All data are transmitted to ACE System CBP.
All ACE Participants can be notified once
the shipment is released or being placed on hold
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Customs Broker submit entry data
and manifest data through CBP
Approved ABI System
P.S, if this is consolidated air/ ocean cargo, either inbounded carrier or broker can transmit associated HAWB within the required time frame. In order to do so, the broker needs to obtain the required customs bond ( type 1.2 and 3)
Therefore, customs release = Carrier e-manifest matches broker submitted manifest data + Entry submitted data is being accepted by ACE System.
Last but not least, there are many ACE Import Manifest Documentation types as there are different types of mode of transportation. Please refer to the details to CBP webpage at
https://www.cbp.gov/trade/automated/technical/ace-import-manifest-documentation
Do I make it simple and clear for you? :)