Both games install and start just fine!
I wonder why so many people report installation and start problems with these games on Steam!?
One common and very possible reason seems to be getting Windows 10 through upgrade process. Removing and re-installing Steam Client seemed to solve those problems for many especially if they had these games before Windows upgrade.
Luckily my Windows 10 Pro installation was fresh and so was the one of Steam Client.
Have not started playing either game yet, actually it would be turn for a non-darkside game - just finished Resident Evil 7 with both endings on Friday.
Happy gaming, everyone!