Can not print an element in an specific position in an arduino list
How about you completely delete

int names[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 


and instead do:

if (attempt != FINGERPRINT_OK)
    return -1;

Serial.println ("Belongs to: "); 
Serial.print(users[data.fingerID - 1]);