Since the switch from SCN to 1DX, the main page of Advantage Database Server are no more existing, but you can still search for the old documents, blogs and questions in the archive of 1DX.
If you are looking for the Version Matrix of Advantage Database Server, you can open this blog.
The Product Download is still t find at the Launchpad. Select at the top menu Download and insert “Advantage Database Server”. After you will get all results for this product, which can be downloaded at SAP side.
The same is also for Knowledge Base searches, if you select in the top menu Knowledge Base and insert your error description or error code, you will find a lot of helpful results.
If you are looking for ALS, Developer Kit or evaluation version 12, please check this blog.