I installed and activated the URL Uploader plugin version 1.2.3 but cannot get it to work.

In Admin I go to Photos > Add > URL Uploader.

I am able to select an album (I assume this is the target album to which photos will be uploaded)

I can enter a URL in the Select files box (the instruction for filling this field is pretty terse but seems to suggest that if I just enter the URL without | <file name> after it then all files at the specified URL will be uploaded)

The Add links button is enabled but all it does is clear the contents of the Select files box.

The Start Upload button is permanently disabled.

Is this a known problem and if so is there a fix?

Looking in Github I see this plugin is pretty old and the original developer stopped coding for Piwigo but appears to have handed it over to somebody else. Can anybody comment on whether this plugin is still maintained and supported by anybody?

Environment

Piwigo 15.3.0 Check for upgrade
Installed on 9 January 2025, 6 days ago
Operating system: Linux
PHP: 7.4.33
MySQL: 5.5.5-10.11.10-MariaDB-cll-lve
Graphics Library: ImageMagick ImageMagick 7.1.1-39
Cache size 91.5 Mo   

Activated plugin list

Batch Downloader
Export Data
LocalFiles Editor
Manage Properties Photos
meta
Read Metadata
Rotate Image
Tag Groups
URL Uploader