To do a systematic literature review, the researcher need to know what she/he is analysing. So, the question need to be defined at first, and all keywords and the search strategy are defined. For that reason, deductive theory is used.
You would be "deductive" in your methodology, i.e., applying your inclusion criteria to individual studies (to decide whether to include or not), but only "inductive" in your conclusions, i.e, generalizing from observations in the selected studies.
Though I strongly agree with Paula Heikkilä, however, I am confused with Praveen Panday answer. Could you plz explain a little bit to your answer? How SLR is mixed method approach?