Go to you team space. If you are an admin, you'll see the "..." under "Files".
If you're not an admin, then you can't install the chatbot.
Click on the "..." then "Other applications", as showed below.
Then type "App studio" in the search bar.
Then install it.
Then choose the bot option
Then click on "Manifest editor" as showed below.
Then click on Create a new app.
Then fill in the form as asked. Here is some info to help you go quicker :
Once finished, the got to Capabilities > Bots
Click on setup
Chose the "Existing bot" option.
Name your bot easily so you can find it afterwards, and choose the options as showed below.
Here is the bot ID : c238f7ec-fa0c-478f-8527-df5b0ea09692
Then go down to finish and click install
Then open the bot
Say start talking to it !