Static website with different locations in dokku

Question

I am using dokku and docker to run my static website. I want to create some subdirectories and locaions using nginx.conf file. This is structure of my files

└── first
    ├── dist
    │   ├── index.html
    │   ├── page.html
    │   ├── ...
    ├── tools

└── second
    ├── dist
    │   ├── index.html
    │   ├── page.html
    │   ├── ...
    ├── tools

And I want my site to be like example.com/first to load index.html in dist folder of first and example.com/second to load index.html in dist folder of second.

So I created a nginx.conf like this:

location /first {
  alias /app/first/dist;
}

location /second {
  alias /app/second/dist;
}

But I get 403 error for trying to get pages and when I go to example.com/first/dist everything is fine for first website. How can I config my nginx.conf file?