If you want to modify the project with your own landing page here is how you can achieve that.

Disable the landing page from the settings page.

In that case you will need to install the landing on subdomain/domain and have the system on other location.

ex on main domain you will have the landing page, that can be wordpress or any html website.

And on subdomain, install the project

ex

example.com → the landing page

app.example.com → the project

Enter www,app in subdomains field.