How do i walk through something but also be able to stand ontop?

(i have made this post on devforum but have gotten no luck)

so recently Ive been working on a game with a tree jumping system similar to shindo’s and i decided i wanted to make tree physics similar to theirs. so i tried looking up about how i could do this and i found a video about collision groups which showed group id 5 as the one i needed, so i eventually tried this and nothing worked, i couldn’t walk through it. so how exactly would one do this?? here is an example of how it works:

https://gyazo.com/c3778ac2ff881c5ee83e35e4eb397aea