Once you've logged into your Google account try a search for "album archive." You have to use the same Google account that you used to create the Picasa web albums, sometimes tricky, because we sometimes have more Google accounts than we realize (I have at least three because a couple of e-mail providers I don't really use migrated their services to GMail and created accounts in my name).
Picasa Web Albums had been going to Google+ Photos (Googles effort to be another Facebook) but I think you would be better off linking your albums to Google Photos, which is more of a image management tool, with online editing. You will lose your Picasa tags and edits, as Picasa maintained this information separate from the image files, and Photos accesses only the image files.
I've not gone through this migration myself. When I started experimenting with Picasa as a local tool, Google Photos had already been set up and was more useful to me, and it was clear that Web Albums were on their way out, as this was already being discussed in Picasa forums in early 2013.
What browser you are using could be a factor. I use Google Photos only with Chrome, and my Chrome default is logging into Googles welcome page, so Photos shows up as one of the apps under the apps icon in the upper right corner of my welcome page. On my phone and tablet, Google Photos has a dedicated app.
Tom Test
Itasca Spirit 29B