The app says:
Checks failed, the program is not installed
and in the terminal:
During checks, file /home/william/.var/app/com.usebottles.bottles/data/bottles/bottles/Epic-Games-Launcher/drive_c/Program Files (x86)/Epic Games/Launcher/Portal/Binaries/Win32/EpicGamesLauncher.exe was not found, assuming it is not installed. Aborting.
I already tried several times, with latest Wine or Soda, with the .msi installer downloaded from their website too.