For me, there is a broken link, @Shenol, fixed.
Another user, Bootloop after installing V0.21 on preinstalled /e/ S9 - #4 by quadcopterman, suggested that the method was not complete.
It is not intuitive that the small button which as @Shenol says reads “Do not install” (on the subject of TWRP.apk) leads to completion of the method. Or are there any other details not intuitive?