Same here in Windows 10 and latest version of Renoise. Gui opens up fine, but in the midi routing of the instrument in Renoise, noting is send to the destination instrument.
I’ve downloaded Renoise demo and it does not work for me either. I’ve opened an issue on LibreArp’s GitLab and will look into it. Maybe I’ll devise a workaround that will allow LibreArp to function properly in Renoise. 
Found the problem: weirdly enough, Renoise does not accept LibreArp’s MIDI output, when it does not have an active audio output channel. I have added a dummy one and it started working. The problem will be fixed in 2.1, which I’m hoping to release soon. I’ll post here when it’s out.
Sounds great, thanks for sorting this out.
That was quick.I will be waiting for the fix
Its working ok but tell me something.I cant move the loop marker to the left if there are notes.Is this normal behavior?

Yes, that is currently the intended behaviour, you can’t put notes outside of the loop area. I’ve had complaints about that before, so maybe in a future update, I will change that.
Its a pain as is because i must delete notes move the marker in order to hear the other parts of the notes and how they could fit it to my song,notes that i really need so its killing the workflow.Make an interesting part that you like but delete notes to hear the others before then draw the previous deleted notes again and so on, you see where the problem is but you have done a marvelous job already so thanks
Yea, I understand why you would want to do it like that, so it is very likely that maybe some version 3.0 will have a better way of editing the loop.
Another issue is i cant save patterns or load.It gives me the option to save i input a name click ok but it does not save it
Update.Sorry my bad i must name the preset with .lapreset
There are many inconsistencies regarding when notes play i must do some further testing.Sometimes it ignores chord changes i dont know what is happening
Update. My bad again it does not skip notes i was sending the midi to a monophonic vst.All seems well
Oh it should be adding the .lapreset extension by itself. This used to be a problem on Linux and it was a bug in the framework LibreArp is based on, but on my end that has been fixed by an update. Which OS are you on?
I am on Solus Os 4.3 Gnome and it does not add .lapreset automatically but this is really not a problem for me
Hi, LibreArp 2.2 is out now and there is this one change regarding loops that I think you’ll like 
Great !!! I will test it when I get home
I am having the time of my life with this sweet sweet tool!!!.Big thank you and i wonder what else do you have in mind for this.
Glad you like it!
If you’re interested, a rough to-do list is on the issue tracker. You can also join our Matrix chat room where we discuss what’s next for the plugin and I put some sneak peek videos there from time to time 
New problem It does not show up in Mx linux in Renoise and Bitwig
If you’re using MX Linux 19, it’s probably because its GNU C Library (aka glibc) is older than what the plugin was built against. LibreArp’s official binaries are built on Ubuntu 20.04 (the current LTS), so it is built against the GNU C Library version 2.31. MX Linux 19.4 has GNU C Library version 2.28.
The simplest solution would probably be installing LibreArp with Homebrew, which builds your very own binaries from the source code using what is available on your system. You can also manually build LibreArp from source if you feel adventurous.