Hi @Januel welcome to the /e/ users forum.
If you check a few posts with the hashtag eosinstaller you will notice that we frequently suggest simply to use the manual install method Install /e/OS on a Fairphone FP5 - “FP5”, particularly with fp5 as the install is done by a script so is not so hard.
Ubuntu may not be equipped for cross platform work. in addition to install of platform tools (preferred method Installing adb and fastboot on a Linux PC) Android SDK offers
Device setting up here is the specific for Ubuntu:
quote
Ubuntu Linux: Set up the following:
- Each user that wants to use ADB needs to be in the
plugdevgroup. If you see an error message that says you’re not in theplugdevgroup, add yourself to it using the following command:
sudo usermod -aG plugdev $LOGNAME
Groups only update on login, so you must log out for this change to take effect. When you log back in, you can use id to check that you’re in the plugdev group.
- The system needs to have
udevrules installed that cover the device. Theandroid-sdk-platform-tools-commonpackage contains a community-maintained default set ofudevrules for Android devices. To install it, use the following command:
apt-get install android-sdk-platform-tools-common
/quote
You realise that the error is one of the most common seen, the installer does not see the phone in Fastboot mode. You need to ask yourself, is the phone in Fastboot mode. An easy test (if you correctly installed platform tools) is
fastboot devices
[HOWTO] a Clear Guide to install "IMG-e-builds" when /e/ web installer fails