$FolderPath = Get-Item -Path "c:\testing\" -Force
[System.Collections.ArrayList]$Report = @()
[System.Collections.ArrayList]$groupLookup = @()

# Enumerate all groups and their members. Prepare for it to take forever.
# Could use search base if you have a specific ou you're interested in or just go wild
foreach ($group in Get-ADGroup -Filter * -SearchBase 'OU=Groups,DC=DOMAIN,DC=COM') {
    $groupLookup += @{
        $group.Name = $group | Get-ADGroupMember
    }
}

# Export for later use?
# $groupLookup | ConvertTo-Json C:\Testing\groupLookup.json

Foreach ($Folder in $FolderPath) {

    $Acl = Get-Acl -Path $Folder.FullName

    foreach ($Access in $Acl.Access) {

        # split DOMAIN\USERNAME and select the last item in the array (USERNAME)
        $groupName = (($Access.IdentityReference).ToString()).Split('\')[-1]

        $Report += [PSCustomObject]@{
            'FolderName'       = $Folder.FullName
            'AD Group or User' = $Access.IdentityReference
            'Permissions'      = $Access.FileSystemRights
            'Inherited'        = $Access.IsInherited
            'GroupMembers'     = $groupLookup.$groupName
        }

    }
}

$Report