1- First, you need to use this link to login Zoom marketplace; https://marketplace.zoom.us/ (Use your Zoom Credentials to Log-in)

2- Once when you logged-in type 'Timer' to search field

3-Click the button for Approve use of this app

4- If you need app permission, please accept it and click Visit Site to Add

4- Allow Permissions (see the picture below)

5-Lastly, check your Zoom Applications to use it.