but i got this error msg

The error message is your error message.

I suggest you look at $PSItem within the catch to see the actual error.

The warning shown is generated by your catch block, so it does not reveal the original exception. The existing suggestion to inspect the error record is the right first step.

There is also a separate return-value issue in the calculation: the currently documented Get-PnPUserOneDriveQuota returns a numeric byte count. Its implementation declares OutputType(typeof(long)). You should divide the returned number directly, rather than read $cuota.StorageQuota.

This version checks the CSV header, reports the original exception message, and skips blank usernames or a missing quota result:

[CmdletBinding()]
param(
    [string]$CsvPath = 'C:\Temp\lista1.csv',
    [string]$OutputPath = 'onedrive_cuotas.csv'
)

$usuarios = @(Import-Csv -LiteralPath $CsvPath -ErrorAction Stop)
if ($usuarios.Count -eq 0 -or 'username' -notin $usuarios[0].PSObject.Properties.Name) {
    throw 'The CSV must contain at least one data row and a username header.'
}

$resultados = @(foreach ($usuario in $usuarios) {
    $account = ([string]$usuario.username).Trim()
    if ([string]::IsNullOrWhiteSpace($account)) {
        Write-Warning 'Skipping a row with an empty username.'
        continue
    }
    try {
        $quotaBytes = Get-PnPUserOneDriveQuota -Account $account -ErrorAction Stop
        if ($null -eq $quotaBytes) {
            Write-Warning ('No quota was returned for {0}.' -f $account)
            continue
        }
        [PSCustomObject]@{
            userEmail = $account
            cuotaMB = [double]$quotaBytes / 1MB
        }
    }
    catch {
        Write-Warning ('{0}: {1}' -f $account, $_.Exception.Message)
    }
})

$resultados | Export-Csv -LiteralPath $OutputPath -NoTypeInformation -Encoding utf8

For example, a returned value of 1TB produces 1048576 in the quota column. PowerShell's 1MB is 1,048,576 bytes, so this column is technically MiB despite retaining the original cuotaMB name.

I checked the CSV, conversion and error-handling paths locally on PowerShell 7.6.6 with a mocked PnP command: one successful row, one simulated error, a missing quota, an empty username, and a missing username header. I did not connect to your tenant or reproduce its authentication/permission failure. The original exception message and the actual CSV headers are still needed to determine why your call fails.

-ErrorAction Stop makes non-terminating cmdlet errors catchable by try/catch.