How use Sharepoint add-ins with PowerShell without installing Sharepoint?

I'm writing a powershell script to copy files from sharepoint to a windows computer location. I don't want to install sharepoint on a windows computer to run this powershell script. We only need it on the server that runs our sharepoint. The purpose of my script is to copy files from sharepoint to a windows computer as backup.

I'm following this example. However, when I run it (with the add-psSnapin) , I get:

"Add-PSSnapin : The Windows PowerShell snap-in 'Microsoft.SharePoint.PowerShell' is not installed on this computer."

I was looking at this article, and it seemed to take the Enable-PSRemoting, which I added in my script.

This is my script to far, which is just like the link I gave above:

#run 64 bit powershell version as administrator (doing this): https://stackoverflow.com/questions/19055924/how-to-launch-64-bit-powershell-from-32-bit-cmd-exe 

Set-ExecutionPolicy RemoteSigned #permission to run scripts
Enable-PSRemoting
Get-PSSnapin -Registered | Add-PSSnapin -Passthru
#Add-PSSnapin Microsoft.SharePoint.PowerShell

$tempSource = "http://sharepoint.college.edu/sites/Disaster%20Plan/Forms/AllItems.aspx"
$ToLocation = "C:\Users\mcl8\Documents\2018\powershellFiles\toLoc\"

$web = Get-SPWeb -Identity "http://sharepoint.college.edu/sites/Disaster%20Plan/Forms/"
$list = $web.GetList("http://sharepoint.college.edu/sites/Disaster%20Plan/Forms/AllItems.aspx")


function ProcessFolder{
   param($SourceUrl)
   $folder = $web.GetFolder($SourceUrl)
   foreach ($file in $folder.Files) {
      #Ensure destination dir
      $destinationFolder = $destination + "/" + $folder.Url
      if (!(Test-Path -path $destinationFolder))
      {
         $dest = New-Item $destinationFolder -type directory
      }
      #Download file
      $binary = $file.OpenBinary()
      $stream = New-Object System.IO.FileStream($destinationFolder + "/" + $file.Name), Create
      $writer = New-Object System.IO.BinaryWriter($stream)
      $writer.Close()
   }

} #ProcessFolder

#################start here##################################

#run this as administrator

#Download root files
ProcessFolder($list.RootFolder.Url)
#Download files in folders
foreach ($folder in $list.Folders) {
   #ProcessFolder($folder.Url)
}

It's failing on Get-SPWeb as follows:

Get-SPWeb : The term 'Get-SPWeb' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

I tried uncommenting the Add-PSSnapin line, but get this failure:

Add-PSSnapin : The Windows PowerShell snap-in 'Microsoft.SharePoint.PowerShell' is not installed on this computer.

But, like I said, I don't want to install Sharepoint on my computer.

Any ideas how to use the sharepoint add-ins? Thanks!