Create a page and add a data grid to it then select the data source as microflow and pass this microflow over there , but before this change the return type of your current microflow to a list and pass the list which you have retrieved via retrieve activity , and finally call this microflow from navigation .
As the error states “Parameter 'Location' of the selected microflow does not match available arguments”, the page where you are using the datagrid, must have a dataview with entity location. Then inside that, you can have a datagrid. This is because, you have Location as the parameter for this Microflow. In this case, I dont even see the need for datasource microflow if Location and office is associated.
If you want to have datagrid only in your page without dataview for location, then you cannot have the Location parameter. And the Datasource microflow must be returning the list of all Offices.
Probably doing the same assignment as you collegue here: https://forum.mendix.com/link/questions/101519
Take a look at the give solution of Ananthi A and my addition to it.