I just wanted to install the Skype for Business Windows application using wine. But somehow the installer crashes all the time. Not sure if this has something to do with the fact that it seems that this .exe would just download all the needed files first. Is here a proper way to install Skype for business on Ubuntu 18.04?
That's the way Microsoft designed Skype for Business, to use shortcuts and programming tricks instead of documented system calls which WINE can handle. The WINE website documents how Skype for Business does not work under WINE, but a commercial alternative is available for Linux.
There are 2 alternative options I am aware of.
One is to use https://www.tel.red/linux.php Sky. The free version lets you screen share for up to 2 minutes, same for voice and video. It's a bit of a pain if you need it for more than that without paying.
There is also the SIPE plugin for Pidgin if all you want to do is chat.