In English, the expression "free spirit" refers to someone who does whatever they want, someone who doesn't submit to rules, authorities, conventions, social obligations, etc. Doing some cursory Googling, it seems to me like "espiritu libre" has the same connotations as the English "free spirit"...? Could someone who is sufficiently bilingual in English and Spanish confirm this?
I also don't know about the semantic range of मुक्त and आत्मा in Sanskrit, but in Hindi, the expression मुक्त आत्मा sounds to me like a soul that has been liberated (eg, from the cycle of rebirth), rather than someone who does whatever they want. If it's the same in Sanskrit as it is in Hindi, maybe there is a better word than मुक्त to be used here? Maybe something like स्वच्छंद?