Further questions:

— In which wallet would you want to import them? Do you run a node or is the SPVs your only option?
— Are the keys related somehow? For instance, is there a master public key in which you can derive them all or are they just arbitrary keys?
— Why do you want to achieve this? (optional, but appreciated if answered)

First of all, he or she imported 14,132 private keys and not 5,000,000. Secondly, you should never install closed-source software outside a trusted place. It could be something malicious and judging by the comments, it's most probably a trojan.