I tried to run AdAway in root mode, but it says I don’t have root access. I then activated dev options on e/OS/ but the root access option isn’t there.
How do I get root access?
Rooting is not done by only flipping a switch in the settings, you need to install a program first which applies the necessary changes to your OS installation.
Since /e/ is based on LineageOS, that would nowadays be Magisk … https://www.xda-developers.com/how-to-install-magisk/.
Rooting can affect how OS updates are to be done depending on your device, if you want the rooting to survive the updates, so you might want to check beforehand by doing a search.
You might also want to check whether what you want to do can be achieved by non-rooting means. Blokada gets mentioned rather often, for instance.