Choosing directory when exporting CSV file using php

Question

I have the following script that will export a csv file locally on my desktop. Now, when customers update their CSV file i want them to be able to save it to their desktop or downloads folder. However, how do you select the relevant pathway that will allow each unique customer to export the file. Potential hurdles, I do not know the username for the customers computer i.e. Users/username/Desktop etc Is there a function where you can select where you want to export the file? (similar to the save function in Word) Because i am currently using a similar function for importing that allows you to select which file that you want to import?

if (!$dbconnect) {
    die("Unable to connect to the specified database!");
} else {
    $sql = "SELECT * INTO OUTFILE '/pathway/ to/save/new.csv'
FIELDS TERMINATED BY '\t' 
LINES TERMINATED BY '\r\n' 
FROM Tablename; "
            ;
    $result = mysqli_query($connection, $sql);

if (mysqli_affected_rows($connection) >= 1) {
    $message = "successfully exported!";
} else {
    $message = "Try again";
    $message .= mysqli_error($connection);
}
    echo $message;
}
}