First, make sure you have yarn / npm installed as well as composer. Also, you'll need the symfony cli program which basically will simplify the PHP server command.
Secondly, duplicate the .env file and create a .env.local file that you can override in order to fill in the right information about the database and so on.
Then :
composer install
yarn install
ornpm install
php bin/console doctrine:database:drop --force
php bin/console doctrine:database:create
php bin/console doctrine:migrations:migrate
php bin/console doctrine:fixtures:load --append
php bin/console cache:clear
yarn encore dev
to make webpack encore watch and compile your js & css filessymfony serve
to start the php development server
OR If you have make installed on your computer :
make install
or make install-dataset