Uploading localhost mysql.sql file uploading problems

You only need to obtain the access token once.

It looks like your code echos the access token, so just copy that (or get a token by clicking the "generate token" button on the app console) and then change your code to just this:

$accessToken = "<the token you obtained>";
$dbxClient = new dbx\Client($accessToken, "PHP-Example/1.0");

(Everything else in the code snippet you shared can be deleted or commented out, since you don't need to do it once you already have an access token.)