To invite a user to your account, you need to create a new team member record for them.
So you can do that a number of different ways. If you're in the my users page, then you can click add new user. That will take you to the team member record, with the option to create any record, immediately popping up. The other way is from the dashboard where you can click the plus in the team member panel. And, again, that'll open the form, or you can just click, from the team member table, the new team member record form.
There's a warning at the top that explains, how and why you will be charged, and that will very much depend on the role that you select for the for the new team member. So login required, as you would expect for pilots, and so on. Login optional. So, this would be for people that don't need to log in to the system, but still need to record it against, jobs, for example, ground crew, camera operators, and so on.
Just enter the email address, first name, last name, and select the primary role. Click save new record, and that person will then get an email prompting them to access the system, set their password, and create their login. And at that point in time, you'll be charged for them if they are chargeable.