The Online Assessment stage…

This stage can vary with companies, and how they carry out their online assessment tasks.

https://www.shl.com/solutions/products/assessments/behavioral-assessments/

The types of tasks I have seen are:

Preparing for these tests:

You do not need to prepare as much for this stage compared to others, as the company will give you sufficient practice material to familiarise yourself with the questions. For the job simulation, make sure to read the companies values and what they want in a applicant, and apply this when responding to the questions - it is mostly common sense.