This page is the fastest honest path from zero to one product whose J2Commerce download file row matches the newest ZIP on disk. Read Requirements first only if you are not sure J2Commerce and PHP versions are already in range.
Confirm Joomla 4, 5, or 6 with PHP 8.1 or newer and J2Commerce installed with downloadable products configured. Set J2Commerce configuration Attachment folder path to the parent directory that contains your free and pro package folders, not to a single package folder inside them. Have at least one versioned ZIP on disk named package_version.zip where package matches the last segment of the folder path you plan to map. Download plg_system_rca_j2c_downfilessync version 1.0.2 or newer from your Pro access at https://recreatinganew.com.
Open System, then Install Extensions, and upload the plg_system_rca_j2c_downfilessync ZIP. Open System, Plugins, and confirm System - RCA J2C Downloadable Files Sync is enabled. If you just upgraded from an older build, install through Extensions with method upgrade so parameters and the map survive.
Open System, Plugins, and open System - RCA J2C Downloadable Files Sync. On the Settings tab, read the How to use note above the Product folder map textarea before you paste lines, because the pipe-separated format is picky on purpose. Find the numeric J2Commerce product ID from the product edit URL or catalog admin. Add one active line in the shape product_id|free/package_folder or product_id|pro/package_folder, for example 19|free/plg_system_rca_themer. Save the plugin.
Open the Sync panel tab on the same plugin screen and click Sync Now while logged in as a Super User. The panel reports per-product results. When a line succeeds, the lowest-id managed product file row for that product should reference the latest versioned ZIP filename.
In J2Commerce, open the mapped downloadable product and inspect product files. The primary managed row should show the newest package_version.zip path without a stale filename from last month. Download once as a test customer or through My Downloads if your shop exposes that path. If Direct Download or another integration still serves an old file, clear Joomla cache and confirm Sync ran after you copied the new ZIP into the folder.
Copy the new package_version.zip into the correct free or pro package folder on the server, run Sync Now again or wait for cron if you configured it, and spot-check one download. The map does not auto-discover new products; you only maintain lines for SKUs you sell.