There is currently an open issue being worked on with Microsoft to update the Zerto Marketplace image. There is no ETA at this time. I would advise you to simply deploy a Windows 2016 or 2019 VM and install Zerto for Azure using the link available on MyZerto: https://www.zrto-dev.com/myzerto/support/downloads/
Please be sure to carefully read the Installation Guide here to ensure that all the requirements are met prior to installing the software.