Following the group is the same as joining BTW. I got a group request which I approved.

i can see that you are following the group.

To join a "public restricted" group the process is :

* you follow the group ( eg @ testgroup @ friendica.u3a.social )
* I, owner of the group, gets an notification ... if I'm happy I'll approve the follow (to you join the group)
* You'll then see other posts to the group and can post to it

Friendia supports different account types :

* Personal - one of standard, soapbox or love-all
* Organisation
* News
* Community group - one of public, public restricted and private

So a group is just a special type of account.

You should be able to go to settings -> manage accounts and click on "Register an additional account". The new account can be changed from personal to community group via settings -> Account -> Advanced account types.

You can also click on the "+" icon in the groups which creates the account in a different way,