I'm 69 and this is my first MMORPG. Try Swamp Haven, its not a large guild and the only requirements are to have fun and be respectful. They're not super active on discord which is fine by me but they are active in-game. They are very willing to help out. I know several of the members are in their late fifties. Here's a discord invite for you to check out.
https://discord.gg/p6NBqMW

Heathen Horde (PC/NA) (+18) The Heathen Horde is currently looking for more members to join our community for Trials, Dungeons, and Social aspects of ESO. We have 4 weekly Trial events and weekly raffles. We are currently at 160+ members. Our community focuses on older adults who struggle to find commonalities with a large percentage of the gaming community at large. Our 3 key fundamental priorities are: -Family -Career -Community We recognize that as we mature more is expected of us and life happens, we are not punitive of our members having to take care of things that matter the most over silly achievements. What we believe in is making the most of the time we have while playing so you can strive to get more out of your gaming experience with less time and effort put in. If our ethics and goals sound like what you are trying to obtain from your guild be sure to check us out over at our Discord: https://discord.gg/v2PCbVW