Here is some added information that may help.
This is my local machine. I am connecting to the database Adventure works dw 2012 that i downloaded and moved to my data folder and "unblocked it".
I created a login for the AdventureWorksDW2012 and used my current login which is (name)-PC. (Also, i was told by someone i had to use the Adventure Works DW 2012 instead of regular adventure works 2012. I dont know if that is true or not)
I have been playing around with the impersonation information and obviously have been getting different errors with each attempt.
Mostly i have been just trying "Use this service account".
When i installed SQL was there any special configurations i missed?
Adventure Works 2012 DW is the one the cube project uses.
Adventure Works 2012 is the transactional sample.
Most cubes have a data warehouse in between the cube and the transactional source.
This has additional business logic, many times to summarize data and will be of a more report friendly structure.
The user you are using must be part of the SSAS admin group.
NT SERVICE\MSSQLServerOLAPService must have access to the Adventure Works 2012 DW.
Grant it owner role and try again.