The link shows various pros and cons, but which download do you select ?
Perhaps this thread would help get your bearings [HOW-TO] Flash /e/-OS on Fairphone 3 using Debian based GNU/Linux
Post #58 is an addendum which shows what to expect from an /e/OS download and the location of flash_fp3_factory.sh.
It is nice to see you here and welcome to the /e/OS forum, but are you aware of https://forum.fairphone.com/