Well, loading a binary can mean anything and converting a bitmap is best done with a paint app like Photoshop or Gimp or something like that. But it was just as well that I asked to check what you wanted because it appears that you don't need to convert a bitmap at all and that what you really want is to move the poles on a map, flood some plains and work with some terrain. I think that Wilbur could be one of a handful of tools that would help in that case.
As said, if it is earth - even post apocalyptic - then the land form, continents and so on would be in roughly the same place and shape as our current earth and so downloading earth data sounds like a good start. NOAA is a good place to go. Also search for SRTM data and you can get binary data for height maps of most of the earth. I believe that it is possible to get some of that into Wilbur or also QGis or possibly using GDAL directly. GDAL is the library which is incorporated into qGIS.
You can use QGis to change a map projection. Its not something I do a lot so cant contribute but I know that Waldronate has a good deal of knowledge about that and maybe Wilbur or a similar tool can do that for you.
If your prepared to do all of the terrain modeling in lower height resolution you can do it all with grayscale bitmaps in a paint app like Gimp. You can lower the heights or raise them and cut off the height at a certain grey level to simulate flooding at a certain level. You can definitely import a greyscale height based image into Wilbur and continue to process it as terrain from there. But much can be done with a paint app until you want something special like erosion etc. Waldronate is certainly the expert here for Wilbur and FT3 and I dont know how to fix your app issues.
But if you want to try QGis then its free and here is the link:
https://qgis.org/
Its a full GIS app which means it is quite complicated and has lots of options, most of which you wont need to use.
Also:
https://dwtkns.com/srtm30m/
https://portal.opentopography.org/ra....082015.4326.1
http://learningzone.rspsoc.org.uk/in.../Download-SRTM
https://geo.javawa.nl/srtm/index.php?lang=en
https://download.geoservice.dlr.de/SRTM_XSAR/
I am sure one of the above will be useful getting the data.