For these public lists, it has to store the csv file somewhere 'public'ish and also where the folder protection settings are such that plugins can store a file.
So the code asks wp for whatever you have specified as the 'uploads' folder in your wp settings and then creates a subdirectory with a 'silent' index.
$upload_dir = wp_upload_dir();
$csv_path = $upload_dir['basedir']. '/users_csv';
If you changed your uploads settings at some point, then the location of the csv file would change. So you can control the location to the same extent that you can control the uploads folder.
I'm loath to create too many settings - makes a plugin feel too cumbersome and it hardly seems like a very necessary thing to be able to change.
If you had some good reason why you needed to be able to control the location, I'd probably look at making the function amr_users_get_csv_path pluggable. would have to test that nothing else got broken.
If it means a lot to you, you could try doing that and let me know, and I'll consider the change for the next update.
alternatively making one could make the user_csv translateable??