that is normal as the web installer only support a few devices, mostly “Murena devices”
posts are editable as a Wiki. Here is the summary : (1) install the appropriate Flashing Tools (2) allow “Non Vendor OS” to be installed on the device (3) Check the communication between the PC and your smartphone (4) Download a custom recovery manager (5) Download an /e/OS build (6) Unlock the Bootloader (7) Flash a custom recovery manager on your device (8) install /e/ from your computer, using the “adb sideload” method or (9) Install /e/ without computer using the “Device-Storage…