I am posting this from memory, so it might be a bit vague.
When looking at the OT dashboard, in the upper right-hand corner there is a button "Link to Cloud" or something similar. Click on the button and it will do a quick check of the sync requirements, click next. A device confirmation window will appear with an eight-character code. This is where I got stuck, because I was looking for the code in the cloud and in my on-prem dashboards, instead click the confirm button. It will then prompt you to log into the cloud, prompt you to name a couple things and you are then done.
After a bit the OT scanner will show up in the Installations on the cloud dashboard and after a bit more time the OT assets will be synced with the cloud.
Linking with Cloud - Lansweeper IT Asset Management