Taking pics with digital camera can be tricky in terms of lighting/shadows. Flatbed scanner should be better. If the old photos are very fragile you likely will need to do something with them to preserve them (scanning is a good option).
We did this for my mom’s funeral recently. My sister (who is crafty/artsy) glued 3 different colors of construction/craft paper to the boards (in a checkboard type pattern) before she attached the photos. And used glue dots to attached the pictures. That worked well.