Hi Natalies. We generate the home feed based on the groups you are following. More explanations are provided here: https://community.tribe.so/question/5dd2642c5036b37cfd8548e216
We have 3 types of groups: Public, Private, Secret. The difference between these 3 types are explained here: https://community.tribe.so/question/5d1e190bbf817a730875ff2024
Giving explanations above, if a content is posted inside a group (regardless of the type of the group) I can only see the content in my home page if I am already a member of that group.
If there is a group that you want all your community members to be a part of it and to see the content generated in that group in their home feed, you can add the group as a default group. More explanations are provided here: https://community.tribe.so/question/5d70380b2ccbf45c66ee942415