Download and unpack (untar) archive - on MS Windows
you can use 7zip, TotalCommander, etc.
Place script in your ~/.gimp-2.10/scripts, or [gimphome]/share/gimp/2.0/scripts/, or
~/snap/gimp/94/.config/GIMP/2.10/scripts/ (in case you use snaps)
Run Gimp and open your images for printing
Run script from main Gimp menu /Tools/Images Grid Layout (at least one image must be loaded!)
Set your specific settings in opened dialog, or let it default and click OK
Print created image
Script settings
size of new image from standard paper sizes or set manually width and height in pixels,
millimeters or inches
size of paper margin - empty space around paper
user defined maximum size of images on the paper(size of place for image in the grid)
minimal distance between grid cells
units for size values
DPI of new image
repeat every single source image x-times on final paper
count of rows and columns in grid of images (size of grid sell will be calculated and images
will be automatically scaled)
positioning strategy - snap image to paper edge, or center image in the grid cell
automatic image rotation for best orientation in grid cell
automatic change of image aspect ratio to grid cell aspect ratio
repeat last image to fill empty cells
flatten visible layers in new image (you can do additional changes to arranged images, if you
uncheck the setting [for example: you can hide some layer with image to print grid without it])
color of foreground (color of empty grid cell)
color of background (color of paper, IOW: color of space between grid cells)