To create a custom data layer from a CSV file, the user needs to have two permissions assigned to the permission group they belong to: Manage Data Sources and Manage Data Layers. These permissions allow the user to upload external CSV files with record and location information, and create data layers to visualize this data in Salesforce Maps1. The user can create custom data layers from CSV files by following these steps2:
Click Layers.
To save the data layer privately so only you can see it, click Saved | Personal. Or, to share the data layer with other maps users, click Saved | Corporate.
Hover over New and select Data Layer.
Name the data layer and select the data source, filter, and style options you want the data layer to show.
Click Choose data source and select Add a Data Source.
Log in to the Salesforce Maps Custom Data Source Portal with your Salesforce credentials.
Click + New to begin uploading a new external CSV file.
Name your data source and click Upload Files to choose a local CSV file to upload as a data source.
Select the location headers and the column headers you want to import from your CSV file, and format the data for each column header.
Click Save and Process to upload your data source to Salesforce Maps.
Reference:
1: Custom Data Sources with Salesforce Maps | Salesforce Help1
2: Create Data Layers | Salesforce Help3