Hi Chris! They used to have this really handy guide available. I can't find it in their current support docs, so hope it's not out of date.
We can process the data extracted from the sections called:
Key Stage 1/2 Steps
Key Stage 1/2 Levels
Contextual and end of key stage data should have come across from your MIS when you imported pupils. You may also want to store a copy of the data under their "Additional Information" section, but unfortunately that's not data we're able to import to Insight.
Alternatively, I believe if you go to Export > Create Backup within Target Tracker, you can generate a CTF (.xml file) which contains historical summative data. You could try sending that across to the data processing team here first, as that might contain everything you need and is much quicker to produce!