If you eve run
composer install and terminal hands and then shows
killed it means the server does not have enough memory to install the packages, this is common if you do not have a composer.lock file in the repository.
IF you do not have a
composer.lock file in your respositoy then should:
compoer.lock is not in a
.gitignore file Run
composer install in a local environment (either your local physical machine, or a development virtual machine)
With the updated
composer.lock file commit the file and push it to your repository.
Then on the server
git pull and then you should be able to do a
composer install using the same versions as you've done locally.