In my experience, it is much easier to convert a DSLR image to FITS than it is to persuade Astrometrica to pay any attention to an embedded WCS.
For JPG and PNG files, nova.astrometry.net will convert to FITS and plate-solve for free. There are any number of free apps to convert from RAW format to something more amenable, including FITS. A very quick search on “RAW to FITS converter” dug up several on the first page.
The major problem with Astrometrica, in my experience, is that it runs natively only under Windoze and barely runs under WINE. I don’t trust the photometry very much either. If the source code were available we could check and perhaps enhance, but it isn’t and we can’t.
Other than that, parts of it are excellent and it is likely what I would use, had I not written a script to track on an object moving from frame to frame.