Download file from AWS S3 bucket / http profile

Hi cpt_ri_F5 , 
Could you please disable any AWAF/ASM Policies if exists , Remove attached iRule and convert Virtual server type to performance layer 4 , If the issue is resolved so , Keep disabling ASM policy and attach http profile again , and test one more time. 
If it works with http profile , so you have issue with AWAF policy and need to check yout policy and AWAF system Variables. 

If the Download didn't work so you the issue is with http profile , and you need really to disable it , in this Case I recommend to add this : 

when HTTP_REQUEST {
    if { [class match [string tolower [HTTP::uri]] contains uri-data] } {
         HTTP::disable
         log local0. "Condition True in Request" 
         return
}
}
when HTTP_RESPONSE {
         HTTP::disable
         log local0. "Response Action achieved" 
}

> I addedd [Log local ] as a guide to make sure that your requests match with Conditions of if statement , and to make sure that http profile really disabled. 
> I added Return to break the irule , and prefer to attach the Pool "MYPOOL" under virtual server resources. 

The Last thing if this available with you, Take a Packet capture for both sides ( Client and server side ) with identifing the Download file request to see why it gives you an empty/corrupted file.

Follow the above steps , I hope this helps you