Hi Hamo,
While the ability to search Project Catalog isn't yet available on Upwork for Clients Mobile App yet, our engineers are working to add it very soon. Meanwhile, feel free to use the mobile version of the site to search Project Catalog on your mobile device.
Edited to update: A button "Catalog" has just been added to the Jobs tab of the App for easy access to Catalog search. We'll continue making improvements to the mobile app experience.
Thank you!