Learning a new program is different for everyone. Some people have any easy time while others struggle. A lot of it depends on how much time you spend with the program and how much good training material you have to work with. If you're going to try and learn by watching Youtube videos then you're probably going to have a hard time.
I can't really tell you what specific program to use, since this is not my area of expertise and I don't know what programs a company like Osprey uses, but if I was going to design a hiking pack, I would use Modo, since I'm very familiar with it, and I would follow the type of workflow shown in the video below.