This is a rather simple achievement that takes a lot of patience but it is not hard to complete.
You need to complete 100 objectives in a single vault. These objectives are shown on the third option on the right bottom tab list (pipboy) next to the room construction menu. Most of them are easy but there are some hard ones too.
You can skip one of them each day for free, you may skip more using quantums but I dont suggest to do so. Just skip the hard ones like "Kill (number) deathclaws without weapons" for example. Also, completing the same objective counts towards %. They appear randomly so I cant tell you anything more.
Finally, my thread
Collect.... under... minutes objective glitch on these specific objectives may help you grind some of them. Happy stacking!
Debug solutions for the people that their tracker is stuck on Xbox One:Try to continue your save on Win10. Idk about the opposite though.
Start a new vault and focus on this achievement. This method is boring and requires more time but it works 100%.