While there is a package for the Welcome DAM supporting CMS 12, there is a separate package for CMS 11
The CMS 11 compatible Welcome DAM code can be found at:
https://nuget.optimizely.com/package/?id=Optimizely.Labs.CMS11.WelcomeDAM
https://nuget.optimizely.com/package/?id=Optimizely.Labs.CMS11.WelcomeDAM
Documentation is available at:
https://github.com/episerver/welcome-dam-cms11
This is an open source style of offering, is a fairly basic implementation, and is provided "as is".
Further support and development will largely be provided in the package oriented towards CMS 12.