Do it in stages and learn along the way...

The program text explained that you can't do anything that takes more than about 10mS... so...

rather than this...

Code:
MAIN:
    if Update = 1 then 
        update = 0
        if second = 0 and minute =  9 and hour = 0 then goto beep1
        if second = 0 and minute = 27 and hour = 0 then goto beep1
    endif
        
    BEEP1:
        sound buzzer,[100,10,50,10]
    
    goto main
If you simply did this...

Code:
Main:
        if (minute=9 and hour=0) then 
		Buzzer=1
		else
	        if (minute=27 and hour=0) then 
			Buzzer=1
			else
			Buzzer=0
			endif
		endif
Then for one whole minute at those two designated Hours and Minutes the Buzzer pin will go high. This assumes you put Buzzer=0 somewhere at the very start of the program when it first comes alive and initialises.

Check if this works for you FIRST...

Then you can work out how you can move on from there and make the pin modulate something in the available time slot to drive a sounder...