Macbook Pro Safari 11.1

Apple never bundled Flash Player in Safari.

To download Flash Player:

1. Launch Safari and navigate to https://get.adobe.com/flashplayer.
2. The page auto-detects the operating system and browser and offers the appropriate plugin, in this case, it's the NPAPI plugin.
3. Click the 'Download Now' button in the bottom right.
4. Flash Player will be downloaded to the default download folder.  On Mac, unless you changed it it's the User's Downloads folder
5. Go to the download folder and double-click on the Flash Player DMG file to mount the DMG.
6. Double-click on the App icon and follow the instructions to install Flash Player.
   1. Mac will prompt you for a user ID and password, this is your systems Admin user and password (What userid & password do I need to install Flash Player? )

In recent versions of Mac OS (who knows about Mojave) Apple included Flash. You do not and cannot download it. Here were the instructions, they might be of help: Enable Adobe Flash Player for Safari