Within Teamwork, you can use file storage integrations to link files from your third party storage accounts to your projects.
If you have enabled the integration with Dropbox, Google Drive, Box.com or Microsoft OneDrive (personal), people on your project with the appropriate permissions will be able to browse the folder you have connected.
They will also be able to add files from that folder to your files area for commenting on, categorising, tagging and attaching to tasks or messages, just like files you have uploaded directly.
In the Files section of your project, click the File Integrations option in the top right and select the relevant integration.

A modal will open listing all of the files and folders within the root folder set for the project. Using the checkboxes to the left, select the relevant files to link to the project.
Click the Link-in Selected Files button in the bottom right to proceed.

A file options modal will open where you can choose a category and privacy for the files.

For certain integrations such as Google Drive, you will see an additional Access tab in the file options modal which allows you to specify how access rights are managed for files located within that integration.
Click Link Files to complete the file linking process. The files will be listed in the project's Files area and will display an icon for their associated file integration. You will also have the option to view the file directly on the integration's site.

Note: Files linked to your site from storage integrations do not count towards your Teamwork file storage limit.
For more information, see: Uploading Files Directly to Your Integrated Storage Apps