You unlock this achievement when you complete your tenth thieving challenge. There are a total of 53 thieving challenges in the game--four in each of the eight chapters and 21 in the six client jobs. Five of the client jobs have four thieving challenges each. The sixth client job has only one.
Whereas each chapter has four challenges, a maximum of two can be obtained through a chapter run. One challenge is always collecting all loot. Collecting loot is time consuming and you may want to go for simpler ones. The remaining challenges in a chapter are dependent on playstyle. For example, remaining undetected requires a ghost playstyle. Thus, you must commit to the required playstyle in addition to meeting the conditions of the challenge. In other words, if you remain undetected but the game tells you that you have played as an opportunist, you will not get credit for the remain undetected thieving challenge.
The client jobs are shorter than the chapters. The thieving challenges tend to be simpler. You can get all thieving challenges in a run except, on the rare occasion, when a job contains challenges mutually exclusive.
You can check your overall statistics by pressing
and selecting Player Progression
followed by Statistics
to tab to Overall. It will show the number of completed thieving challenges.
Although you must pay attention to meeting the conditions of the challenges, obtaining the achievement is not difficult. The client jobs are short. The conditions for the challenges fairly simple. So, obtaining 10 of the 21 possible challenges in the client jobs is relatively easy.