I can join existing groups I just couldn't create a new one.
The group I was trying to make was "I hate when people add me only to get introduced to my single sister" - a stupid group maybe but after it happened like 3 times that I got messages like "Your sister is hot you have to introduce me to her" I got a bit frustrated and tried to create a group about it.
next to the search function is the POST button. Click on it and a drop down tab will appear. Choose EXPERIENCES - you can make your own up. Not very obvious, but that's how it works