P3D v4 uses Add-on.xml method for installing scenery and aircraft, moving away from the old "paste into folders" method.
Lockheed Martin used a clear versioning scheme for v4: prepar3d v4 professional plus 402321468
There is no official version or identifier “402321468” anywhere in Lockheed Martin’s release notes, download servers, or license databases. If you see this number attached to a download link, torrent, or activation tool, it is almost certainly part of an illegal crack, a fake installer containing malware, or a mistyped hash from a piracy site. P3D v4 uses Add-on
You specifically mentioned the Professional Plus edition. Here is what you get over the Standard Academic/Professional license: There is no official version or identifier “402321468”
Note: If you are a civilian simmer, these features are largely invisible, but the license allows you to use them legally.
Launch the simulator and go to Options > Settings. These settings balance visuals with performance.
If you already have a file labeled “Prepar3D v4 Professional Plus 402321468”, delete it immediately and run a full antivirus scan.