[HELP] I cannot manage to install e/os in my android FP6

[piero]

of course you can wait, but it looks unnecessary regarding documentation

@piero

If you plan to relock the bootloader after the installlation

(not mandatoty, only available with Official version, why relocking ?)
Most important thing to take care about is the “android Security Update Patch Level” in the already installed Operating System on your device before you start the install process.

It must be OLDER than the “android Security Update Patch Level” included in the /e/OS build you want to install, otherwise you risk to change your device into Brick.

• You will find this information about stock OS on the device :

settings --> about phone --> android version 15 --> android security update

• you will find this information about /e/OS build on the release article about the /e/OS version you want to install :
  the title of the article need to match both “/e/OS version” and “android level”,
  currently "e-3.3-a15"

Releases · e / os / Releases · GitLab

more detailled explications here : (answered) Install /e/ on FP5 with newer Security Patches