The missing column/attribute name is Calendar and the Reason states the following: "Error: unmapped mandatory column" (imagem below).
The "Calendar" attribute (image below) is a system required attribute of the Facility/Equipment entity and its description is the following: "Fiscal calendar associated with the facility/equipment.".
I haven't set my Fiscal Calendar yet because I read at the Implementation Guide that one can do it only once and in order to work with Sales Quota. I'm guessing I don't need to set it for now because when I mannually create a Facility/Equipment I don't get any kind of Fiscal calendar related error. I'm guessing I have to bypass this issue some how... I will post this at Dynamics Forums, perhaps someone already has been over this.