Within Teamwork Projects, you can integrate your site with Dropbox, and then add the integration to individual projects.
Once connected, you can link to your files from your Dropbox account directly in the Files area of the project, or attach them to tasks or messages like you would with any files you have uploaded directly.
First, you will need to authorize Teamwork Projects to connect to your Dropbox account.
To do this, click your profile icon to the top right of your site, and select 'Settings' from the drop-down menu:
In the Settings area, go to the Integrations tab:
In the Dropbox section, click Connect to get started:
Once you have completed the authorization, you will see an option to select a top level folder:
This allows you to control which files in your Dropbox account are accessible from Teamwork Projects.
When you connect each project to your Dropbox, you will be able to choose this folder for the specific project or set the project folder as any of the ones within this root folder.
For more information, see: Enabling the Dropbox integration on individual projects