Hi, I got the same issue as @FFP3 twice: 2 years ago with a S9 and today with a S8, so I abandoned the Easy Installer and reverted to manual install.
Despite a quick switch between Volume - and Volume +, as described on @aibd 's tutorial, I would still enter the Android recovery.
Both times I solved that by using Odin3 (dowloaded here) to install the TWRP. Still I had the same issue there, but the trick that worked was to disable Auto-reboot while the phone is connected to Odin (on the left in Odin’s window, in the ‘Options’ tab between ‘Log’ and ‘Pit’ tabs). Only with that, I managed to avoid entering the Android recovery.
Then, the TWRP steps are rather easy, but there was a final hurdle: I was unable to copy the .zip ROM file into Internal Storage (and the TWRP folder wouldn’t show up). Maybe I did a wrong wipe? But luckily I had a microSD card, I was able to copy the .zip file onto the card and insert it to support the install, so I solved that.
Again a huge thanks the /e/ team and community for a great improvement in user privacy!!
My comments here are only to help other users adopt /e/OS, not to criticize the wonderful project 