What happens if the 80kg decides to stand near one corner of the platform? Each actuator needs to be able to lift the entire 80kg all by itself.
Are the actuators supposed to be underneath the platform? Can it be suspended from cables above? Can it have tracks up the side and it rides up and down on those tracks?
What side loads are expected? Can the 80kg step off the platform while it's fully raised? The action of stepping off or on will push the platform sideways with significant force.
Depending on the underneath/above answer, I would consider using a single point hoist above or modify a scissor-lift table like you sometimes see used for lifting car transmissions or even entire cars. Converting manual-hydraulic one to automatic-electric should not be too hard if you can find a linear actuator with the required force and travel.