I join Parkeljc's opinion and add a couple of pics.
The walls are quite interesting, muddy soles are not recommended. We were lucky to have nice weather a couple of days before too, so there was only slightly damp forest soil, which shakes off the shoes right away. We had no issues, the girls climbed the C variant, I climbed some D/E sections too, where the loop for resting really came in handy.
For those who want to climb only the F section, it's generally easier to drive to the top by car and descend via C down to the junction (a couple of minutes), you just need to know which cable to follow down, as the path from the start to the F section is quite long. (info from the gentleman who helped build the ferrata).
I had to descend a bit lower (to the branch for Ninotov rov), as my daughter's phone almost fell from the top into the forest under the rock...
After finishing the ferrata, zipline descent, so no descent problems
(descent can be booked and paid online, but reservation needs to be confirmed by phone at TIC, especially for ferrata climbers, as they bring a cart for each individually, set to weight)
No crowds on the ferrata (3.9.2022), we met only 5 people total, and due to the phone incident we were there quite a while. First search I didn't find it - calling the phone (it was set too quiet), then we went to the top (due to reservation at a set time), zipline to the valley and back up by car, and another C descent to Ninotov rov and search via Google's "find my device".
Carinthians are ultra friendly anyway, parking in Črna no problem, cafe open before 7am, so I recommend!!