Employee A notices that there's a broken piece of equipment and wants to submit a work request. This is typically someone who is not involved in the day to day maintenance of the facility. Instead this is normally a employee, cashier, executive, marketing, operator, etc.
For companies that have a lot of employees, we provide them with a dedicated URL, what we call their "Company Request Portal", to submit work requests. So, like you said, they don't need to create an UpKeep account for every single user which would be super prohibitive. Instead they take this link and either embed that web-page in their company website, or have that link saved somewhere all employees know where they can submit a work request.
Regardless of whether the request was made via the "portal" or through the application, the tickets get funneled into UpKeep. It sends a notification to the "Admin" of the group which then has the option to "Approve" or "Reject" the request. When they approve it, they are typically assigning the work order to one of the their maintenance technicians. When the maintenance technician updates a work order, both the admin and the requester are notified about the new status of the request :)