Older Macs (before or early 2010) do not have the required instruction set to use the current versions of a third party component that Yate embeds. Starting with Yate v6.8, whenever this condition is detected, you will be directed via the application update mechanism to a 100% functionally equivalent version. Subsequent updates will work as expected.
The installed version will have an OM appended to the build number in the About Yate panel.
While you should never have to manually install the OM version it can be downloaded here.
Macs running macOS 10.10 and 10.11 will not have up to date SSL certificates. (Unless they've been manually updated). This causes the standard activation and deactivation processes to fail. For those of you with this issue you can do a Manual Activation or Manual Deactivation. These methods are web based and execute on a server which has up to date certificates. More information on the manual workflows can be found in About Activating, Deactivating and Migrating.
As we are personally suffering with unsupported hardware which is forced to run older OS versions, we feel your pain. The OM version and the manual activation/deactivation workflows are an attempt to keep you running.