Members with the Administrator role can always approve anyone’s entries.
However, there are two different options for setting up which time logs will go to which Manager for approval:
First option:
If you wish for the Managers to only approve entries for the users of their teams, you need to create Teams with users.
Then set up at least one user as a Team Manager. They will approve the logs of all members of the team they manage.
<<< Read more on different User roles or Teams functionality >>>
Second option:
For the Managers to be able to approve and reject entries of all users on the projects assigned to them, you need to set them up as a Project Manager instead: