Apparently there may be a browser caching issue that contributes to the 15.2 -vs- 15.3 dmg download confusion.....the initial link posted had the wrong info at Apple's end, and they have since corrected their link.
I just tried clicking on the initial link to the combo download in the first post of this thread and was getting the 15.2 result....then manually navigated to the download page on the Apple Support site, selected the 15.3 combo for download and GOT THE SAME 15.2 miscue!
Using the develop menu, I cleared Safari caches and clicked the SAME link to successfully get directed to the 15.3 combo updater dmg download.....my browser had cached the original mis-matched link and was NOT going to let me get to the corrected link until I cleared my browser cache.
