To use Gantt (Beta), you need to enable this feature through Feature Console. By enabling this feature, you can use Gantt (Beta) to add and manage project tasks and project task assignments.
To enable Gantt (Beta):
Click Perform in the Action column of either step 3 or step 4, depending on the page layout that you are using:
You must wait for the step to complete.
[Optional] Assign the PSA Project Manager-Gantt permission set to users trialing Gantt (Beta), and then click Mark as Done. If not needed, click Skip.
(on). The Messages panel displays a summary of the changes.To add the Gantt (Beta) button manually to a page layout, add the button from the Mobile & Lightning Actions list to the Salesforce Mobile and Lightning Experience Actions section.
You will also need to assign permissions to users to enable them to access, and view, or view and edit Gantt (Beta). For information about how to do this, see Assigning Gantt (Beta) Permissions.
Related Concepts
Gantt (Beta) Setup and Security
Related Tasks
Assigning Gantt (Beta) Permissions
Gantt (Beta) Configuration Options
Configuring Gantt (Beta) Custom Settings
Reference