This will install a version of Dropbox on a Windows OS that has Powershell support

dropboxpowershell-installer.ps1

#Dropbox Powershell installer
#Version 3.2
#Download and install the latest version of Dropbox for the purposes of Enterprise deployment

$source = 'C:\source' #Change this to a download directory of your choosing
$arguments = '/s' #Change /s to /NOLAUNCH to prevent client start

#Check to see if the user has the Administrator role on the machine, if not die
If (-NOT ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole(`
    [Security.Principal.WindowsBuiltInRole] "Administrator"))
{
    Write-Warning "You do not have Administrator rights to run this script!`nPlease re-run this script as an Administrator!"
    exit
}

Function Get-RedirectedUrl {
    Param (
        [Parameter(Mandatory=$true)]
        [String]$url
    )

    $request = [System.Net.HttpWebRequest]::Create($url)
    $request.AllowAutoRedirect=$true

    try{
        $response=$request.GetResponse()
        #Write-Host $response.ResponseURI.AbsoluteUri
        $url = $response.ResponseURI.AbsoluteUri
        return $url
        $response.Close()
    }
    catch{
        "ERROR: $_"
        break
    }
}
#Delete old installer files
Remove-Item($source + "\Dropbox%20*.exe")
$url = Get-RedirectedUrl("https://www.dropbox.com/download?full=1&os=win") #This is the current Dropbox offline installer URL
#Find the Dropbox client version number from the registry
$client_ver1 = Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\DropboxUpdate\Update\Clients\{CC46080E-4C33-4981-859A-BBA2F780F31E}\' | Select-Object -ExpandProperty pv
$client_ver2 = Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Dropbox\Client\' | Select-Object -ExpandProperty Version
#Check to see if both version numbers match the version in the URL
If (!($url -match $client_ver2 -And $url -match $client_ver1)){
     #Strip the URL to leave the file name
     $fileName = Split-Path $url -Leaf
     $destinationPath = $source + "\" + $fileName
     $webClient = New-Object System.Net.WebClient
    [int]$trials = 0
    do {
        try {
            $trials +=1
            Write-Output "Downloading Dropbox"
            $webClient.DownloadFile($url,$destinationPath)
            break
        } catch [System.Net.WebException] {
            write-host "Problem downloading $url `tTrial $trials `
                       `n`tException: " $_.Exception.Message
                       exit
        }
    }
    while ($trials -lt 3)
<#
     $webClient = New-Object System.Net.WebClient
     Write-Output "Downloading Dropbox"
     $webClient.DownloadFile($url,$destinationPath) #>
     Write-Output "Installing Dropbox"
     Invoke-Expression -Command "$destinationPath $arguments" 
} else {
  Write-Host "Dropbox client already installed... exiting."
  exit
}
<#MIT License

Copyright (c) 2017 John Bradshaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.#>