If you are using the current release version of the software from the web site, v2.11, you should be able to take a scan of a slide. Using ‘spiral’ scanning is often best, but the inputs for scan size are frames in x and in y. This is used as expected for raster and snake scans, but for spiral one of the numbers is ignored, and the other is used for the number of ‘rings’ in the spiral. You get a lot more images than you might expect!
With a directory of scanned images you can use image software to stitch the images together.
The core team is currently working on a complete overhaul of the software as v3. This will include automatic scanning and stitching. It is not yet stable enough for release, and has a number of features missing. It is currently going through alpha pre-releases. If stitching is important for you, and you understand that alpha pre-releases are not stable and can be broken, then there is information on the latest v3.0.0-alpha3 on the thread OpenFlexure Microscope v7.0.0-beta5 and Server v3.0.0-alpha3