First off, you need to make sure you are the owner of the bot.
Go onto the platform and scroll down to the page, until you get to Extras in the left hand bar. Click on "Share bot access".
Click on the "Create Invite" button at the top right hand corner of the page, which will then bring up up a URL (as seen below).
Simply email this URL to the person you want to invite - and remember it's one URL per person. They'll then get the link and access to the bot. Easy!
Once someone has received your invite, they will be asked to either log in to their Bot Platform account, or create a new one.
Once they have followed the sign up process the bot should show like below.
If they are signing up for the first time they will need to click, 'send verification email'
If you are unable to see the email, please check in your spam folder.
Once your account is verified your account is fully functional.
You can withdraw the invitation at any time by clicking the red "Withdraw" button. If the invitation has already been accepted, you can still revoke access, as seen below.