accessing my sub-domain's control panel

I am new to WP.

We have a WP site, and I wanted a copy of this site to serve as a sandbox for testing purposes.

Our host (Dreamhost) created a subdomain for me, so now we have:
https://www.mysite.org and https://www.sandbox.mysite.org

The are each connected to their own database.

I can’t figure out how to access the sandbox’s control panel.

For our main site it’s: https://www.mysite.org/wp-login.php

What would it be for the sandbox site?

Thanks!