How to batch add folders to Folder Actions
This following AppleScript code will ask you to choose the script file to attach then we'll give you two separate options for adding multiple folders to attach that script file to

This works for me using the latest version of MacOS Mojave.

property pathToFolderActions : ((path to workflows folder as text) &amp; "Applications:Folder Actions:")

tell application "Finder"
    set resourceName to (choose file with prompt ¬
        "Choose The Script File To Attach")
    set resourceName2 to name of resourceName
    set folderActionScript to (container of resourceName as text) &amp; resourceName as string
    try
        duplicate resourceName to folder pathToFolderActions with replacing
    end try
end tell

activate
set theFolders to (choose folder with prompt ¬
    "Choose Folders" default location (path to desktop) ¬
    invisibles false ¬
    with multiple selections allowed)

activate
set chooseAgain to button returned of (display dialog ¬
    "Would You Like To Choose  Additional Folders?" buttons {"NO", "YES"} ¬
    default button "YES" with title ¬
    "Would You Like To Choose  Additional Folders?" with icon 1)

if chooseAgain is "YES" then
    activate
    set moreFolders to (choose folder with prompt ¬
        "Choose Folders" default location (path to desktop) ¬
        invisibles false ¬
        with multiple selections allowed)
    set theFolders to theFolders &amp; moreFolders
end if

repeat with i from 1 to count of theFolders
    set thisItem to item i of theFolders
    tell application "Finder"
        set nameOfTriggerFolder to name of folder thisItem
        set attachFolderActionTo to (container of thisItem as text) &amp; nameOfTriggerFolder
    end tell

    tell application "Folder Actions Setup"
        activate
        try
            set addedFolderAction to make new folder action with properties {name:nameOfTriggerFolder, path:attachFolderActionTo}
        end try
        try
            delay 0.5
            tell addedFolderAction to make new script with properties {name:resourceName2, path:(pathToFolderActions &amp; resourceName2)}
        end try
        if not folder actions enabled then
            set folder actions enabled to true
        end if
    end tell
end repeat

delay 5
tell application "Folder Actions Setup" to quit