When moving to Arbor, only Statutory Key Stage data (Standardised Assessments and marks for students in these assessments) can be migrated. You can see where to find this information here: DfE statutory Primary Assessments
We don't migrate any other assessment types into Arbor, because they have different formats in different applications. You also cannot import using a CTF.
We won't automatically bring over assessment from external systems, such as Target Tracker, Educater etc.
You'll need to set up marksheets and input or import your baselines, marks and targets to track and analyse your assessment data. Get started by following these Introduction to Arbor Assessments guides: