It was sold out on the basement level that other people posted.
They told me to go up to the first floor and buy it.
So I asked at the information desk and they told me to go here.
Here you can get bus (subway) tickets and Roma Pass.
I guess I have enough.
These days, I mostly buy and use tickets here.
Please take note.
There are two locations on either end of the first floor of Termini Station.
This is one of them.
I also received a lot of help from many people.
I’m posting this because I want to share some helpful information.