This script will scan through a list of UNC’s and it will locate any folders or files that are older than 90 days. You can change the amount of days by editing the $gtdays variable.

$servers = Get-Content "\\SERVER\"
$gtdays = "90"
$timeformat='yyyy/MM/dd hh:mm:ss tt'
$time = (Get-Date).ToString($timeformat) 
$drive = "v"
$drivemapped = $drive + ":"

$username = 'USERNAME'
$password = ConvertTo-SecureString -string 'PASSWORD' -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential -argumentlist $username, $password

foreach($server in $servers) {
    
    #cmd /c net use v: $server  | Out-Null
    New-PSDrive -name $drive -psprovider filesystem -root $server -Credential $cred  | Out-Null
    $date = Get-ChildItem $drivemapped| Sort-Object -Descending -Property LastWriteTime | Select-Object -First 1
    $days = (New-TimeSpan $date.LastWriteTime $time).Days
    #cmd /c net use v: "/delete" | Out-Null
    Remove-PSDrive $drive | Out-Null

    if($days -gt $gtdays) {
        New-Object –TypeName PSObject -Property @{
            'Server' = $server
            'File or Folder Name' = $date.Name
            'Date'= $date.LastWriteTime
            'Days Old'= $days
        }
        
    }
    else {
              
    }   
}