Installation of 4.9 full version on Mac

Dear FF++ developers and users ,
I tried to install the full version of FF++ on MacOS 4.9 but didn’t succeed it keeps telling me that he can’t find a way to open it.
I have a MacBook pro and the MacOS version is Big Sur 11.2.3
I also installed a text editor for Mac named “TextMate 3”.

can anyone please, explain me how to install the last version of ff++ and how to use the text editor in order to run FF++.

Thank you,