"''The Great work, for probationer is to obtain scientific knowledge of the nature and powers of my own being.''

Is initiation necessary to attain spiritual goals noted in the Mystical and Magical System of A.A?
In my country here is no magical order so this is very important for me."

I am convinced that the best results (i.e., most successful and easiest) result from working formally within the system, under direct supervision.

Nonetheless, one value of the book is that the whole system is provided in a way that one can follow on one's own. One can still make substantial gains on one's own. There is a higher standard required in "busdting your own bullshit" and being careful not to be overly impressed with early results. (The early pages of Liber O are quite useful in this regard.)

Possibly this will even give you everything you need. In the worst case, it will provide you substantial foundation.

@Follower said

"''The Great work, for probationer is to obtain scientific knowledge of the nature and powers of my own being.''

Is initiation necessary to attain spiritual goals noted in the Mystical and Magical System of A.A?
In my country here is no magical order so this is very important for me."

I think it is. But you can have Initiation without others. You can have an Initiation on the Astral plane.

You can be a Mystic as well as a magician.

There is no law beyond Do what thou wilt.