For me much of the difficulty came from some aspects of 5e not being explained. ( I don't have DnD experience)
I completed a full playthrough without knowing what advantage/disadvantage actually did.
I had a whole string of terrible rolls on my character while my friend seemed fine and it turned out that wearing armour that you are not proficient in is far worse than just not getting the +2 proficiency bonus - giving you disadvantage on basically everything.
Despite those issues, managed to get through the EA fairly easily. Once I figured out that wearing things you're not proficient in is horrifyingly bad, I had a much easier time.
Seems I've played about 3-4 runs with different setups and never felt the need to recruit a 4th team member, I think it's really not too bad once you understand the systems.
The only bit that had an issue for me was the minotaurs and big spider, but I think that was because I lacked the action economy only fighting them with two characters when they could multihit. And I didn't attempt to ignore them which is possible, I wanted to take them out.
