UCSC packages/tools ucsc-netchainsubset and ucsc-fatotwobit not working on GNU/Linux
Short answer: respect the case of the tool name

Longer story below

Thanks to terdon, I printed the PATH when the conda environment was active and listed what was in the folder where conda installed the UCSC tool.

ls /mnt/home2/miska/cr517/anaconda3/envs/ucsc-netchainsubset377/bin
c_rehash         libpng-config      mysql_config    openssl  pngfix
libpng16-config  my_print_defaults  netChainSubset  perror   png-fix-itxt

Then I typed netChainSubset and got the help page, suggesting the tool is installed and working. Interestingly, on Mac, the tool is also called netChainSubset but it seems it can be called with netchainsubsetor NETCHAINSUBset for that matter. The case doesn't seem to matter on mac. To make my code more portable, I am going to follow the case in the bin of where the tool is installed.