Hello and welcome to RoR.
Enemy addon for most, is recommended because the default party/warband frames with no add-ons is honestly just very terrible.
If you wonder what Enemy does better than the standard partyframes the list is quite long but some of it is:
1 You get a move visual representation of when members are "near" you. What classes are in each group.
2 Additional important debuffs like "Word of Pain / Boiling blood" timebomb debuffs are shown.
3 Tracking which allies in the party/warband have a blessing, debuff on them.
4 Easier to see who is guarded in the party.
5 Healdebuffs, both ingoing & outgoing effects shown with red/green colored icons.
6 Staggered members shown with a little star looking icon, letting you know if teammembers are unable to play. (CC)
7 Gaurded targets are shown for the partymembers, and guarding tanks can see better who needs their help.
And that is just the visual party frames. And for that alone i think the addon is a must-have for any party/warband player who wants these sort of information, so when you learn what each little bubble, icon and color mean you get fast acces to information that the standard UI doesnt give you.
On top of having better visual, and informative party frames you can also mark players/npcs with the three little prebuilt color arrows. And the option to change color or add more markers. Allowing you to mark the warband leader, to see their location when action hits and stuff get chaotic. You can put an arrow over your Guard, or guardee to better stay within range. Or if you notice a really dangerous enemy player you want to be aleared by their location in future battles you can mark them too.
These two core features, make Enemy a really really solid addon for information.
The rest of the features are useful to some, i think new players will find them overwhelming and would advice to turn them off for now.
MY suggestion for Enemy settings:
after installing the addon and loading up the game, click the little red/white Target icon next to your minimap.
Go to "Configuration"
Under "unit frames" you can change sieze, colors and stuff on your partyframes. If you dont want to fiddle with it, use the standard settings they are more than fine!
For lower rigs, players who want more frames in biiig fights go to "Combat log" tab in the scroll menu. And disable everything. What this tab does it pharsing and tracking your combatlog and every action happening to you. If you are not doing too much analasys of the combat log, dont bother with this stuff.
If your screen is looking like a mess after installing Enemy because you see the old standard Party/warband groups and Enemy groups at the same time then go to;
hit "Esc" go to "costumize interface" then in the "interface" tab to the top right click on the "layout editor" and in the new window click on "Start" editing" middle button.
Here is a screenshot of how the overwhelming mess might look like. But what you want to do it clicking on each of the group/party boxes showing the standard UI and "hide Window"
so only the Enemy window with allies is showing.
https://imgur.com/a/bzNLB7V