On a guess (from the error message it gave that contained a slightly different .so file name!) I tried the following:
I copied the file libfgbuni.so to the new name libfgbunid.so in the same location.
The Linux directory I chose (to contain both .so files as well as the FGblib subdirectory) was this:
The I ran Maple 2020 (64bit Linux) and prepended libname with the subdirectory's location.
This is what happened:
libname := "/home/acer/mapleprimes/FGb/FGblib", libname:
Path set to /home/acer/mapleprimes/FGb/FGblib/../libfgbunid.so
FGb/Maple interface package Version 1.68
JC Faugere (Jean-Charles.Faugere@inria.fr)
Type ?FGb for documentation
[ModuleUnload, cpu, date, fgb, fgb_gbasis, fgb_gbasis_elim, fgb_gbasis_lm,
fgb_hilbert, fgb_interface, fgb_matrixn, fgb_matrixn_radical,
fgb_matrixn_radical2, fgb_multi, fgb_normalForm, pseudo_fgb_normalForm]
[y + x, y + y]
The tar file from the website unpacked and contained the file libfgbuni.so, but when I tried all the above without copying to the new file name I got only this:
Error, (in pack_fgb_find_path) cannot find a valid path !
That is why I tried copying the file to the new name libfgbunid.so with the name containing the extra character.
This looks like an oversight/mistake by the author (3rd party). Also, I notice that on the webpage the example does not show the printing of the discovered file location.