According to the Salesforce Maps documentation1, to create a data layer, the admin must first select either the Personal or Corporate folder in the Layers tab. The Personal folder is for saving data layers privately so only the admin can see them, while the Corporate folder is for sharing data layers with other maps users. After selecting a folder, the admin can hover over New and select Data Layer, then name the data layer and select the data source, filter, and style options. If the admin does not select a folder before attempting to create a layer, all of the options will be greyed out and unavailable. Reference:
1: Create Data Layers | Salesforce Help1

According to the Salesforce Maps documentation1, when using the limit areas by attribute option during an optimization, some units may be trimmed from the areas and assigned to a specific area or the unassigned bucket, depending on the leftover unit assignment setting. To visualize these leftover units, the user must open the alignment using the "Include Unassigned Units" option, which will display all units in the data set, regardless of whether they are assigned to an area or not. This option can be found in the Alignment Settings window, under the Data tab2. By selecting this option, the user can see the leftover units on the map and in the legend, and decide how to handle them. Reference:
1: Optimization in Salesforce Maps Territory Planning | Salesforce Help1
2: Alignment Settings | Salesforce Help3

The three Salesforce Maps products or features that should be included as the implementation partner scopes the project for the prospect are Maps Core, Territory Planning, and Marker Layer Builder. Maps Core allows users to analyze their Salesforce data through geographical visualization and identify where their highest value prospects are. Territory Planning allows users to design territories that promote fair distributions of work while eliminating gaps in coverage. Marker Layer Builder allows users to create custom data layers and identify where their top-selling products are being sold. These products and features are explained in the Salesforce Maps Products document.

The user should tap the refresh button located at the bottom of the map to display additional accounts. This button reloads the marker layer data based on the current map view and filters. This is useful when the user changes the map view by zooming in or out, or panning across the map. This is explained in the Interact with Salesforce Maps on Mobile document.

A Consultant should recommend Publish to Salesforce Fields as the publish method in Territory Planning for a client who uses account owners as the primary method of territory assignment and has low influx of new accounts. This method allows users to update any field on any object with the territory name or ID. This can be useful for clients who want to assign accounts based on ownership and do not need to update them frequently. This method also works well for non-contiguous territories, as it does not rely on geographical boundaries. This is explained in the Publish to Fields in Salesforce Maps Territory Planning document.