Method Spatie\MediaLibrary\MediaCollections\Models\Collections\MediaCollection::setCustomProperty does not exist.

[krutsednar]

$loiItem = Media::where('model_id',$user->id)->where('collection_name', 'applicant_user_letter')->get();
$loiItem->setCustomProperty('zip_filename_prefix', 'users/'.$user->code.'/user_letter'); 
$loiItem->save();

$mediaStream =  MediaStream::create($user->code.'.zip');
$mediaStream->addMedia($loiItem);

I'm trying to create a subfolder in my zip but it throws an error
Method Spatie\MediaLibrary\MediaCollections\Models\Collections\MediaCollection::setCustomProperty does not exist.