To share a document folder with a user follow the below steps:

Step 1: Visit the Company Docs URL.

Step 2: Click on the "share" icon.

Step 3: After clicking on the share icon window pops up appears which allows you to select project "Users" and "permissions".  

Step 4: Click on the "Save" button.

Note: If you enable "Email Notification" then that assigned user will be notified about the shared document.