For openbullet, you could try using wine (the linux-to-windows emulator) to get it to work in ubuntu. If you google some tutorials on wine it should be pretty easy to figure out.
There is an offical Openbullet forum, should be some tutorial and stuffs their.
https://forum.openbullet.dev/topic/348/openbullet-on-ubutu-18-04
Check this below thread, it will help you! 
!