I've never heard of the Sage Timberline data source before. However it does seem related to other forum questions about Sage, including this one regarding Sage MAS 90: Connectivity to Sage Mas 90 Database Issues
It seems that Sage has renamed Timberline to MAS 300 (see Sage product list). Perhaps searching for the new product name can help you find drivers, documentation, etc. that allows you to connect from Tableau via "Other data sources (ODBC)".