Private/Get-ManagedCredential.ps1

function Get-ManagedCredential ($creds)
{
    $credential = Get-StoredCredential -Target $creds
    if ($credential) { return $credential }
    else {
        do
        {
            Write-Host("You have to create a Windows Generic credential before proceeding, read more about how to use it here:") -Fore Yellow
            Write-Host("https://sharepointrelated.com/2018/06/12/powershell-easy-secure-office365/") -Fore Yellow
            Write-Host("")
            $creds = Read-Host "Enter a valid Generic credential name"
            $credential = Get-StoredCredential -Target $creds
        }
        until
        ($credential)
    }
    return $credential
}