Create login and grant access:

Open up SQL Server Management Studio [login to the database engine]>
Security >
Login (Right click) >
New Login >add user: "NT Service\MSSQLServerOLAPService">
select the database being analyzed in the drop-down list at the bottom >
User Mapping [click on the database in the list] >
In the window database role membership click on db_datareader [this grants access to read the data]