General question about autoit capability

I am new to AutoIt. I am wrting a script in powershell using selenium. The script logs into a web console using Firefox. The console has few buttons. One a specific  button is selected, it generates a pop up window that has 2 buttons "Save File" and "Cancel". If you click the "Save", it will save the file into a local directory.

My script can log into the web console and click on the button. But, I do not know what too use to click on the pop up. The pop up is a standalone, not part of the web console. After you click the "Save", it dissapears.

Someone told me that Autoit can be used. I tried it, took the tutorial. But so far, it seems that it can act on windows or pop ups that it creates. I didn't see anything from the tutorials and examples that indicates I can use Autoit for my purpose.

Any experts to comment, suggest or help ?

Thanks