"not just...but" here means same as "not only...but also?"
Native speaker’s answer
Rebecca
Yes, that's right! "Not just" and "not only" have the same meaning, and "also" can be used with "but." Ex: I'm not only tired, but I'm also hungry. = I'm not just tired, but I'm hungry. Ex: The party's not only going to have a buffet, but it's also going to have an open bar. =The party's not just going to have a buffet, but it's going to have an open bar.