As you can see for yourself the plants are not healthy and deprived of sunlight. This can be seen from the floppy leaves and it does look dehydrated.
The reason why the seller gave you those tips is because these typical VFT plant stocks in Malaysia are obtained from one supplier who imports the plants, grow them in the highlands and sell them to all nurseries throughout Malaysia. In their mind the plants come from the cool highlands, therefore it cannot receive direct sun as it is too hot.
The VFTs that are grown in Cameron Highlands do not need to be placed on a water tray as the environment is humid and it rains often in the highlands. Water in the media do not evaporate that quickly in conditons there.
The seller also have fans blowing at the plants because they want to mimic the conditions in the highlands. However, they fail to realised that in a town/city where the plants are placed now, humidity is very low. It is made worst when the fan blows on the plants. In the highlands were winds blow often it does not matter as the air is humid and the wind blows with the mist.
Show the seller these pictures below. They are grown under direct sun the whole day and placed in the garden.
Plant grown by TS
Plant grown by hongrui
VFTs must be given as much direct sunlight and as long as possible. The media must not be dried out.