it's necessary AFAIK
Not necessarily. The SAS Megapatch (I assume you mean the direct-to-4.12.2m update megapatch) is only necessary if the person installing ModAct 5.3 doesn't have version 4.12.2m—if they already do, then the Megapatch is superfluous.
I installed SAS Modact 5.3 and AI Flyables, JGSME Options. Game crashes at 60%.
I tried installing SAS Modact 6.3, same result. please help me.
What game version was the installation which you try to install these mod activators upon? ModAct 5.3 is only for version 4.12.2m, and ModAct 6.3 is only for 4.13.4m. If you tried both, got 60% crashes with both ModActs, and you didn't edit the air.ini, it's possible you've just installed ModActs which were made for the wrong version of the game. Check which game version you have and make sure you're using the correct ModAct for that version.
i can't find find the [Console] section in conf.ini .
Go to the top of the file and press Ctrl + F. Type in "[console]" and make sure that "match case" is unchecked and "wrap around" is checked, then click "find", and one of two things will happen.
1) You will be moved to the [console] section
or
2) The text editor will not find the [console] section. That would be very bad, and mean that your conf.ini is broken.