it says file is not executable

[ARBS-hmm]

Lenovo\AppData\Local\nvim-data\lazy\cornelis\ftplugin\agda.vim[17]..function nvimhs#start[35]..remote#host#Require[10]..<SNR>45_buildStartAndRegister[24]..<SNR>45_ifHashDiffersBuildAndStart[13]..<SNR>45_startAndUpdateCache, line 6: Vim(return):E475: Invalid value for argument cmd: 'C:\Users\Lenovo\AppData\Local\nvim-data\lazy\cornelis\.stack-work\install\be5f9163^M/bin/cornelis' is not executable

something is wrong with the file
Is there a fix?

[isovector]

You're probably the first person to try this on Windows :) The communication here is handled via https://github.com/neovimhaskell/nvim-hs, who might be better people to talk to about what's going wrong.