Missing .env

Make a copy of .env.example, place it in the same directory as composer.json, and name it .env, then populate the variables.

It should look something like the following, but contain your API keys:

STRIPE_PUBLISHABLE_KEY=pk_test...
STRIPE_SECRET_KEY=sk_test...
STRIPE_WEBHOOK_SECRET=whsec_...
DOMAIN=http://localhost:4242
BASE_PRICE=1000

You can use this command to get started:

cp .env.example .env