I have always used the Classical Greek keyboard of Manuel Lopez to write ancient Greek in Windows.
On the Mac however, this keyboard doesn’t work for me conerning for the diacritics. Normally, a/ would result in alfa with acute. But on my Mac, its just an alfa with a slash.
I tried som other keyboards of Keyman, but they all won’t combine the diacritics with the vowel.
The new beta 12.0.7 of Keyman for Mac is intended to address this problem. You can download the beta version from https://keyman.com/beta
Install the beta version as you would normally. You may need to restart your Mac first if the Keyman input method is in use.
After installation, you may also need to do the following, after installing the 12.0.7 beta version, in order to reset the security settings for Keyman, as the reason Keyman was not working is that Apple introduced new security protections in a recent update for macOS (known as Notarization), and Keyman prior to this was of course not notarized: