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As the documentation you linked states:
This read-only object contains all ContentDocument objects associated with an object.
For more information, see AttachedContentDocument in the Object Reference for Salesforce and Lightning Platform.
If you go there, it says:
Use this object to list all ContentDocument objects attached to an object via a feed post.
...
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There's no way to do this without custom development. Data Loader targets exactly one object per data load.
You'd have to build a staging table and automation to transform it into a custom object + attachment, but that's a very bad idea because you'd dramatically limit the size of the attachment you can include due to governor limits.
Abandon the idea of one ...
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Yes, those limits are globally applied. Note that some APIs will have a lower limit, such as a ContentVersion created by SOAP (which will be limited to about 37MB because of the 50MB payload limit), but using specified APIs, such as creating a ContentVersion using REST API with form/multipart will support 2GB file sizes.
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