Here are the instructions on how to set up these preset files into your FL Studio's Effects Category for Selecting an Effect in the Mixer.
BEFORE YOU BEGIN!!!
In order for these presets to work, you have to make sure that the Plugins are Loaded correctly from the Plugin Manager.
In FL Studio, go to Options > Manage Plugins
In The Plugin Manager Window, MAKE SURE YOU SELECT ALL OPTIONS (In Red.)
This is required in order for Waves to unload the "Waveshell" Plugin, which in result, will have an option for each of the plugins to be it's own VST plugin preset.
Normally, You would have to open "WaveShell1-VST3 12.7_x64v", then in it's own wrapper window, you would have to select the Plugin from the list, however; By having the effects as their own "VST plugin preset," you would be skipping that extra tedious step.
This is required in order to use these presets, because the preset files that you will download, are essentially those same "VST plugin presets," except I've manually organized them into folders to make things easier for us all.
If you are still experiencing loading issues when opening the presets, the only thing I can make a guess of, is that you are using an older version of Waves Mercury, or maybe you're trying this on a Mac for some reason, despite the "Windows" in the title.
After you have the Waves Plugins Verified and as it's own "VST Plugin Preset" you can then do the following:
Step 1 : Download the files
Step 2 : Unzip the files
Use 7Zip if you do not have a way to unzip files from your Windows Computer. Right click the folder, and see if there is an option to "extract" if so, then don't bother downloading 7Zip if you do not want to. Up to you!
Below is an example of extracting the folder with 7Zip
Step 3 : Locating Your FL Studio's Effect Plugin Folder
In FL Studio's Browser window, click on the pathway called "Plugin database"
Then right click on the tab called "Effects"
After, click on the option that says "Open"
You should end up with a new explorer window that shows your Effects folder's contents
Step 4 : Drag The Folder Over
Drag the folder over to the Effects folder.
Step 5 : Give It A Try!
Go into your Mixer window, and in the FX slot for any Insert, click to open the plugin list.
For Best Organization, you can set your Plugins to show as a Tree Format
~Justin Omoi ^_^