This paper explores the adoption and use of AI chatbots by knowledge workers in the Italian legal sector. Distancing from existing literature, which mainly explores chatbots as interactive agents and focuses on implications for human agency, in this research, we focus on chatbots as text manipulation tools that knowledge workers have to work with. We collected data from a sample of 39 respondents exploring causal factors influencing the usage behaviour of knowledge workers. The results of a fuzzy set Qualitative Comparative Analysis show two causal configurations of knowledge workers profiles willing to use AI chatbots: innovative-minded employees with a positive attitude towards innovation and workers who approach chatbot usage with critical thinking and in a teamwork setting. Our research has implications for research and practice, on the need to progress investigation of the lack of perceived risk of AI chatbots, and on the role of intensity of usage on the perception of chatbots.