When you export data from the portal, first go to 'Settings' to set your time zone. You can change the time zone with each export if you have users in different time zones.
Next, you may filter data by device ID or user email along with a date range.
Set the filters and click "Request Export." All exported files can be found in the right side menu under "Data Exports." From here, you may also re-download files you previously exported.