Hello, I had the same problem, as Ronnz98 said, try installing /e/ os by following the instructions given on Lineage website:
On this smartphone, do not install twrp, only install /e/ os recovery (or lineage recovery, it will also work the same for installing /e/ os from it).
What is not said in the procedure is that you can install the os from the recovery without using sideload but rather by using the recovery menu “Apply update” . You need to copy the os ROM.zip file on the smartphone internal storage to see it in this menu.