I have this model with the 6 hooks, which has a width of 51 cm. The width of the suspension is 2 cm and this fitted my door without any problems. The door is a good 7 cm thick in total, but it consists of 3 parts and the suspension is only via the innermost (i.e. the 3rd part of the door layers) - and this is only 1.5 or max. 2 cm wide.
This means, however, that the specification here at Galaxus of 5.5 cm or 8 cm width is incorrect. You can see that the shorter model has only 4 hooks, the wider one 6.
Hope this helps.