I'm not at all sure that I can answer you question properly but this I've learned.
If it's a Bluetooth barcode scanner, there should be a way to follow the scan with an Enter, a Tab or Return character which can take you to the next field in the tab order of your layout, but I'm not sure there's any way of getting the scanner to click a Continue button. I think that's because on iOS, the Scanner has taken over the one channel for data entry. It has to exit from that input channel before the virtual keypad can be enabled. You can, however, use you finger to touch an on screen button without needing tp disconnect the scanner from the input channel.
A different approach is to have your database running a script which pauses in Find mode waiting for input to a particular field when you invoke the barcode scanner. Completing the scan with an Enter will then continue the script and process the find. The attached screenshot shows the script steps that we use on the desktop.
I have not tested that this also works with the file running on an iPad with FM Go but could try that later today.
I hope this helps somewhat but you'll likely get a more authoritative answer from someone with wider exerience than I have.