Falcon 4.0 is includes as a “goodie” for Falcon Gold in your GOG library after purchase. They said that they didn’t include it as a separate game as the last official release, 1.08, had too many bugs and caused too much problems, especially on modern hardware, to be considered as proper release by their standards and they would not be able to fix it themselves.
The GOG version works with 4.33 (and worked with 4.32 too) without any problems. You indeed do have to install the original Falcon 4.0 first, but after that you can just copy and backup the .exe, which is the only file needed by Falcon BMS installer.