Create a categorical drop down for the field "company"

To add a categorical drop-down to a dashboard, you need to select "Add Element" from the dashboard and then choose the "Categorical Dropdown." 

For the purposes of this example, a quick search of the schema will demonstrate that the Company field resides on the Users table. To create the filter, simply drag the company field into the dimensions box and select "Refresh Data." Assign a name to the filter (we suggest "Company") and leave the remaining configuration steps alone (1. data type: text 2.multiple values checked ON and 3. default to: all values).