The "First Post" of a thread usually contains links to the base game and major expansions. However, for the most recent incremental updates (e.g., version 1.37 or later), you should skip to the last few pages of the thread where users share "hotfixes" and minor version updates.
Enter "Europa Universalis IV" or "EU4" in the search box. csrinru eu4 updated
Look for the most recent updates in the thread, which usually indicate the latest version number (e.g., v1.38.x). The "First Post" of a thread usually contains