Hi Uli --
I decided to update my paid copy of Sibelius First and discovered that Avid has renamed the product line -- and has re-used the name "Sibelius First" to refer to the free, lower-than-entry version. The Sibelius product line has three members:
Sibelius | First (a free version derived from "Sibelius")
Sibelius (formerly known as the paid version "Sibelius First")
Sibelius | Ultimate (the full version)
I recommend checking out Avid's comparison chart. The free Sibelius | First, for example, can handle at most two verses (lines) of lyrics, no sound library, and doesn't have any plug-ins. Some of the plug-ins are quite useful, like the plug-in that creates capo'ed chord symbols.
Avid have gone to a subscription model, so expect more confusion. The Sibelius purchase, download and install process took almost two hours. I went to Starbucks while the sound library downloaded.
It took forever to install the Avid Application Manager; the actual Sibelius install was faster. I have neighbors who work at Avid. Good thing it's hot and we're all stuck inside...
Sibelius | First is free anyway... Try before buy.
All the best -- pj