There are two ways to access a client folder:
1) From the dashboard, click on the account name.
2) From any page in the app, hit the search bar in the top which says "Jump to Client". Enter the client name and click through.
If you cannot access the client folder, this is likely because:
You do not have permission to view this folder, based on your organisation's settings. Please contact your account manager if you're unsure.
The client folder has not been created yet. You can read how to create the client folder in this article.