In this article, an overview of SSAS workflow was provided.
Please note the following:
The original data does not need to be stored in Microsoft SQL
SSAS can read data from OLTP or data warehouse databases.
OLAP Cubes are stored in SSAS databases.
OLAP are not relational whereas OLTP are relational databases.
summary, I hope that the foundation has been laid down for going deeper into
the UDM before creating your first SSAS project.