Hi Ano,
as far as i understand, you are not using the CheckMK appliance. If you would, you could setup a HA system right away as the appliance has all required features.
https://checkmk.de/cms_appliance_usage.html
or
If you use the non-commercial version, you need to set up things on your own. Personally, if you require HA and want that supported by Tribe, you should investigate the option to upgrade to Tribe appliances, either virtual or HW.
That way - you ensure support by the vendor.