Hey welcome back!
This is very doable in the CYS editor. Dungeon Stompage! does something pretty similar to that D&D style character creation if you want to check out an already published example. I'd recommend checking out the Basic and Intermediate Scripting articles under Help & Info for more details on how to make these variables work.
In terms of limiting the points, the easiest way I can think of right now is create a separate variable storing the points remaining for distribution and decrement this every time the reader assigns a point value (and increment it if the reader unallocates a point, if you choose). Another way is to keep a running total of your reader's already assigned variables (CHA + STR + DEX + ...) and use page scripts to check if this running total matches or exceeds the allocation limit you choose. There are certainly more ways to accomplish this (and perhaps more optimal ones at that), but I'm on the road and can't play around in the editor right now to check. The way I mentioned is probably the simplest to wrap your head around if you don't have much coding experience though.
With that being said, you'll be using the variables in conjunction with link restrictions to prevent the reader from selecting more options should they run out of free points to distribute. Like I said before, Help & Info has many articles on how to accomplish this exactly, and in the Advanced Editor itself there are some informative tips on what certain things mean. The "How to Use Scripting to Improve your Story" article is also a good read for how to change page text and link destinations depending on variable values (such as certain character traits), which I'm sure is something you're interested in for a trait-based storygame.
Let me know if this helps or if you have any specific questions. Good luck! :)
