Google Picasa is retired now, your old albums are only available in the archive. But nothing is lost! You can still use Event Gallery to display your Google Photos images on your Joomla! website.The trick is to mark your album as public or protected. There is no way to do that using the Google Photos website. But there is help: https://www.svenbluege.de/picasa/v1.1/. Use this website to get your albumid, userid and the picasakey. You can change the visibility of your albums too. This tool is build into Event Gallery 3.6 (working version here with a subscription) so you can select your events directly.