On a fresh composer install of Symfony I got errors on installing Sonata admin:

composer create-project symfony/website-skeleton bla ^4.4.4
cd bla
composer require sonata-project/admin-bundle

leads to a problem including: sonata-project/admin-bundle 4.x-dev requires twig/twig ^2.12

The problem can be resolved by downgrading twig before installing Sonata: composer req twig/twig:"^2.12"