To download/install OpenCulturas just run composer create-project --remove-vcs drupal/openculturas_project example.org and then create a symlink for public which links to example.org/web. I believe you need to remove the public directory before you can do it.

Then you can install it via browser. Use the credentials from credentials.txt for database. When installed, it is better to replaces the strings in web/sites/default/settings.php with getenv('CLOUDRON_MYSQL_HOST'). So that you can create a copy, and it uses the new credentials and not the credentials from the other app.

So, I did the following:
Following https://new.drupal.org/download, I installed the CMS, composer create-project drupal/cms. Previously I had been installing and trying to work with just Drupal Core... but I was thinking that since OpenCulturas IS a full CMS, I may as well install that. Maybe that is the main key here.

Then I followed steps from Luckow.

• switch to the www-data user su www-data
• change directory to /app/data cd /app/data

I skipped the following (from Lucknow's post):

• install drupal via composer composer create-project drupal/recommended-project
• move everything from inside recommended-project into the root of /app/data mv recommended-project/* . & mv recommended-project/.* .
• remove the default public folder and make a symbolic link rm -rf public& ln -s web public

and instead installed OpenCulturas from the /app/data...actually, to be honest I've lost track of where I ran the command:
composer create-project --remove-vcs drupal/openculturas_project example.org

And it seems to have been installed in a directory called example.org.

And followed the next poster, Shai's suggestion:
rm -rf public & ln -s cms/web public. So, I'm not sure where OpenCulturas is actually running from! cms/web or example.org/, and to be honest, I don't feel like redoing it all, at least not now.

So, Derpal is installed and running the Events form of OpenCulturas.

www-data@aeb12796-98b8-44ad-9108-5b61d48a8fe7:~/cms$ php vendor/bin/drush cr

# Support bash to support `source` with fallback on $0 if this does not run with bash
# https://stackoverflow.com/a/35006505/6512
selfArg="$BASH_SOURCE"
if [ -z "$selfArg" ]; then
    selfArg="$0"
fi

self=$(realpath $selfArg 2> /dev/null)
if [ -z "$self" ]; then
    self="$selfArg"
fi

dir=$(cd "${self%[/\\]*}" > /dev/null; cd '../drush/drush' && pwd)

if [ -d /proc/cygdrive ]; then
    case $(which php) in
        $(readlink -n /proc/cygdrive)/*)
            # We are in Cygwin using Windows php, so the path must be translated
            dir=$(cygpath -m "$dir");
            ;;
    esac
fi

export COMPOSER_RUNTIME_BIN_DIR="$(cd "${self%[/\\]*}" > /dev/null; pwd)"

# If bash is sourcing this file, we have to source the target as well
bashSource="$BASH_SOURCE"
if [ -n "$bashSource" ]; then
    if [ "$bashSource" != "$0" ]; then
        source "${dir}/drush" "$@"
        return
    fi
fi

"${dir}/drush" "$@"

BBUUTTT of course it isn't working. AANNNDDD I of course don't really know why.

It looks like even Drupal is installed via composer these days - https://new.drupal.org/download. So, do I make a LAMP app, leave it bare, then run composer to install Drupal, and then install OpenCulturas using composer again? Or, do I install OpenCulturas via composer all by itself straight into the LAMP app? Thanks for any tips.