Did your Easy Installer show v-0.20 or v-0.21 in the very top of the window ? Edit you first tried the very old v-2.0, not a typo! 
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Of course we don’t know exactly why Easy Installer v-0.20 was withdrawn; there are preexisting Easy Installer issues https://gitlab.e.foundation/e/backlog/-/issues/?label_name[]=Easy-installer, maybe you hit one of those.
Once you get used to the differences Fairphone manual install https://doc.e.foundation/devices/FP5/install look in many ways simpler than a Samsung.
For education, unzip the download and you can see and read the install script inside.
You would have to be very careful to look out for the differences between FP3 and your FP5, but this seems a nice intro to the Fairphone method. [HOW-TO] Flash /e/-OS on Fairphone 3 using Debian based GNU/Linux