Verified answer

to get it alone應該是指「獨自地去買或拿取某物」，而不想或不需要他人的陪伴或干擾，例： I'd rather get it alone than carry you down the street.

(我寧可獨自去買，也不要載著你滿街跑)

另一個和它很接近的口語化片語是：

Go it alone! 獨自去做(幹)！，例：

Sam decided to go it alone due to his increasingly hectic schedule.

(因為行程愈來愈緊湊，他決定獨自去做)

If you're determined to go it alone, read this manual first.

(如果你已決心自己動手來做，那就先讀這本操作手冊)

get it alone找單幹