It will not be too difficult to find the cache, use the hint. But it might be difficult to get inside, because from time to time, entrances get boarded up. But I trust you will manage to find an opening. ;)
Required: good shoes ( a lot of broken glass on the floor), gloves, a flashlight, climbing skills (you might need to climb thru the window). And bring a friend - it might get spooky in such a big building alone.
I recommend you to explore the whole building, but it might take all day. Try to find: the clinic, procedure rooms, SPA center with a sauna and a pool in the basement, civil defense bunker, narrow underground tunnel which leads to the next building, basket ball hall, stuck elevators and various other shafts, go on the roof to see the amazing view of Druskininkai, and of course - try to explore all the living rooms.
Building was set on fire several times so be especially careful in those areas.
The container is a small lunch box with a logbook, pencil and some tradable stuff. FTF prize: a possibility to become rich.