Yarn permission denied on Eleastic Beanstalk?

Question

I'm trying to deploy an app from a node monorepo on Elastic Beanstalk and seem to be stuck.

I've installed yarn in my environment and trying to run a build command (custom command using a task monorepo task runner):

Procfile

web: yarn turbo run start:server

In my server logs I'm seeing a lot of permission denied errors:

May  2 20:25:42 ip-172-31-32-247 web: yarn run v1.22.18
May  2 20:25:42 ip-172-31-32-247 web: $ /var/app/current/node_modules/.bin/turbo run start:server
May  2 20:25:42 ip-172-31-32-247 web: mkdir /var/app/current/node_modules/.cache: permission denied
May  2 20:25:42 ip-172-31-32-247 web: ERROR  yarn.lock: mkdir /var/app/current/node_modules/.cache: permission denied
May  2 20:25:42 ip-172-31-32-247 web: error Command failed with exit code 1.
May  2 20:25:42 ip-172-31-32-247 web: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

I think these errors are due to my enviroment trying to install the packages as a non-root user. With npm you seem to be able to add a .npmrc file with unsafe-perm=true to your root folder and get it to work. With yarn however, this does not seem to work.

I don't seem to fully understand what is happening and why I'm seeing these errors and am very thankful for any help?