A simple PS script to install ADB/Fastboot (aka platform-tools) directly from Google and add the the binaries to PATH.

install.ps1

function Update-UserPath([string]$Value)
{
    $currentPath = [Environment]::GetEnvironmentVariable("Path", [EnvironmentVariableTarget]::User)
    if ($currentPath -like "*${Value}*")
    {
        Write-Host "The value '${Value}' already exists in user PATH, no update is needed."
    }
    else
    {
        $targetPath = $currentPath + ";${Value}";
        [Environment]::SetEnvironmentVariable("Path", $currentPath + ";${Value}", [EnvironmentVariableTarget]::User)
        Write-Host "Updated user PATH from '${currentPath}' to '${targetPath}'."
        Write-Host "Make sure to restart your applications to get the updated PATH."
    }
}

## Main

if ($Env:OS -ne "Windows_NT")
{ 
    throw "${Env:OS} is not supported by this script at this time.";
}

$downloadUri = 'https://dl.google.com/android/repository/platform-tools-latest-windows.zip'
$workspacePath = Join-Path $env:LOCALAPPDATA 'adb-tools'
$tempPath = Join-Path $workspacePath 'tmp'
$binPath = Join-Path $workspacePath 'bin'

mkdir $workspacePath -ErrorAction Ignore | Out-Null
mkdir $tempPath -ErrorAction Ignore | Out-Null
mkdir $binPath -ErrorAction Ignore | Out-Null

Write-Host "[1/4] Download latest platform-tools from '${downloadUri}'..."
$archivePath = Join-Path $tempPath 'platform-tools-latest-windows.zip'
$ProgressPreference = 'SilentlyContinue'
try
{
    Invoke-WebRequest -Uri $downloadUri -OutFile $archivePath
}
finally
{
    # Bad implementation of a progress bar...
    $ProgressPreference = 'Continue'
}
Write-Host "Done."

Write-Host "[2/4] Extracting downloaded platform-tools..."
$extractPath = Join-Path $tempPath 'platform-tools-latest-windows'
if (Test-Path $extractPath)
{
    Write-Host "Extract path '${extractPath}' already exists, removing..."
    Remove-Item $extractPath -Recurse
}

Expand-Archive -Path $archivePath -DestinationPath $extractPath
Write-Host "Done."

Write-Host "[3/4] Installing platform tools..."
$platformToolsPath = Join-Path $extractPath 'platform-tools'
if (Test-Path $binPath)
{
    Write-Host "Install path '${binPath}' already exists, removing..."
    Remove-Item $binPath -Recurse
}

mkdir $binPath | Out-Null
Copy-Item -Recurse -Path "${platformToolsPath}\*" -Destination $binPath
Write-Host "Done."

Write-Host "[4/4] Updating user PATH..."
Update-UserPath -Value $binPath
Write-Host "Done!"