Yes, the open source edition is free to use. You will need to setup a dedicated or cloud server to host and configure the same. If you want host with a Zimbra hosting partner, you will need to purchase a subscription from a BSP partner in order to receive support and access to the latest features and updates.
What server does is used to host Zimbra OSE?
The minimum requirements for OSE server:
– CPU: 2 GHz or higher (x86 64-bit)
– RAM: 4 GB or higher
– Disk space: 40 GB or higher
– Operating system: CentOS 7.4+ / RHEL 7.4+, Ubuntu 16.04+ LTS,
Follow this step by step guide on on how to install zimbra in centos 7 follow our detailed blog post on this topic.