Infrared sending not working slight misconfiguration?
There are two basic things wrong here - one with your understanding of the timings, and the other with your understanding of how IR communication works.
First the timings - those are both ON and OFF timings. You don't just turn on for a defined length of time - you turn on for a defined length of time and then turn off for another defined length of time.
So for the timings in your code 4507,4507,573,1694,573,...etc... you would:

Turn on
Wait 4507us
Turn off
Wait 4507us
Turn on
Wait 573us
Turn off
Wait 1694us
Turn on
Wait 573us
... etc ...

You have no &quot;off&quot; time in your code, only ever on times.
Secondly is your understanding of IR communications. It does not involve turning an LED on or off for defined times. It's not as simple as that. Instead you are controlling the modulation of an LED.  When the LED of an IR remote control is &quot;on&quot; it's not just turned on - it's rapidly turning on and off. The receiver looks for the presence or absence of this rapid turning on and off light. This is the &quot;carrier frequency&quot; of the signal and must match what the receiver is looking for.
Typically this is between 30kHz and 50kHz depending on the receiver.
So you need some way of generating that rapid on-off signal. Normally this is done using PWM by the IR libraries and switching between 0% and 50% duty cycle for the off and on periods of the signal you want to send.
So it's far simpler to just use a library that does all this underlying work for you.