Landing page subscription does not work

Hi, I am still building my site using ‘Apparent Collective - Berlin theme’ and I have yet to publish it. Meanwhile Shopify created a default landing page, and it is this page I need to access - where will I find it located on Shopify please? Please also note the current landing page for my site does not work when I tried to subscribe.

I have not been able to carry out any edits when I followed instructions below >

“To access your default landing page in Shopify, go to your admin panel and click on Online Store > Pages. Your home page is typically listed there. You can also customize it by going to Online Store > Themes and clicking Customize.” ??