Export

There are many ways to export the data from ManicTime. You can:

export all data by timelines from Tools -> Export. Keep in mind that if you select a big date range (a year or more worth of data) this could be a lengthy process and a big file.
Shift or Ctrl select lines at the bottom left of day view. Then copy and paste to some other app like Excel.
export data from Advanced search.
export data from Timesheet.
export data and images from Statistics.
get all data from ManicTime server via services.

And you can also get the data from the database. To get to the database, go to Tools ->Adv -> Open db folder. Database is in file ManicTime.sdf. You can use this tool to view the data.

Command line export

You can export activities from command line while ManicTime is running. So you could have some script which could get the activities, then process them further.
To get the help for export, run this command where ManicTime.exe is installed.

mtc help export

Command line export

So for example:

mtc export ManicTime/ComputerUsage c:\export\tags.csv /fd:2018-01-01 /td:2018-03-01

Export folder needs to exist. In above example, c:\export folder needs to exist, before you run the command.