If I were you, I’d go to a repro-house and ask them to scan and print it. Anywhere with e.g. an HP Designjet plotter or scanner could do it for you. You might be able to have it printed on a paper similar to the original as well. Then you can put the original somewhere safe and enjoy the print. I’d guestimate cost ~$100-$150
If you prefer to try and do it with your phone, or a camera, then P. Boersting is spot on with outside on a cloudy day. If you use an iPhone/iPad, you might use the Notes app, which will square each shot up as a sort of ‘faux’ scan. I’d shoot from above, so you’ll need something flat to put it on. You can leave it rolled and work your way through it. So the area/work-surface you need isn’t very big. You need to get the paper as flat as possible and always centre the lens above the area you’re shooting. Get a large sheet (A0) of white card or board to use as a reflector, which you need to place on the side opposite to the brightest part of the sky. You’re looking for the flattest light you can get. Make each shot as similar as you can. You can aid the alignment process by simply putting 4 Post-its on the paper at the corners. This will make it easy for the software to align and also for you to visually check. Once aligned, you can simply ‘rubber stamp’ the Post-its to remove them. I’d do the pano/alignment 2 images at a time, although it might work in a ‘oner’. Won’t hurt to try. I think Affinity is best at alignment/pano.