I added it to my cart and completed the "purchase".
From there I chose the Windows download option.
a .install file is now in my downloads folder.
The instructions are a bit interesting:
"Download the plug-in installer if you want to use the plug-in with Studio One. Once the download has completed, launch Studio One, then drag & drop the .install file into the Studio One application window and follow the onscreen instructions."
The pop-up asked if I wanted to install the VU meter. I choose Yes. I tried to Activate it but got a 200 error. The Installation dialog said I needed to restart Studio One in order for the installation to take effect, so I clicked on the button to do that.
I can bring up the Installer and it shows VU Meter, but it doesn't look enabled, so I clicked on the "Enable" button. It didn't seem to do anything.
On the MyPresonus page I downloaded an offline license file, but can't find a way to apply it to the plug-in (which isn't showing up for me, either)
The Solution: Open the Studio One menu. Select "Activate Purchased Items".
At this point I selected the .license file I'd downloaded. You may be able to do this online.