For a one-time inventory intake, the two-file upload is usually the fastest path. Prepare one catalog/current-inventory file and one item-level sales-history file.
If the Data page in your workspace already displays an approved live connection, you may authorize it there. Provider availability varies; support will not promise Shopify, Square, Lightspeed, or another source unless your workspace shows it as available. Square and Lightspeed workflows may ask for unit costs before margin analysis can finish.
Manage or remove a supported connection with the controls on the Data page. CMP support can explain the steps but cannot connect, disconnect, or change a source for you. For a one-time client handoff, default to upload unless CMP has explicitly asked for a live connection.