Rails - joining a github project with a missing database

Rails - joining a github project with a missing database

I am trying to collaborate on a project which has the following .gitignore:
# Ignore bundler config.
/.bundle
# Ignore the default SQLite database.
/db/*.sqlite3
/db/*.sqlite3-journal
# Ignore all logfiles and tempfiles.
/log/*.log
/tmp
# Ignore other unneeded files.
database.yml
doc/
*.swp
*~
.project
.DS_Store
.idea
.secret
So the database is missing, along with all the related files, which makes
rails throw me an error if I try to start the server, and I also get rake
aborted! errors if I try to run db:create/migrate/ etc (yml file not
found, adapter not specified).
Any pointers at how can I tackle the problem in the most correct/effective
way?