I've had the same problem and some correspondence with the onion team who have been really quick and helpful in their responses.
Speaking with the team they've explained that the Onion Cloud was originally developed as a free sandbox resource for hobbyist developers to create web-based projects for light usage. This was always an add-on from the initial offering of onion and the main development process for these boards is using the built in systems locally (http://Omega-XXXX.local/), now OnionOS (More details at https://onion.io/2bt-onion-os/ ).
Their technical team are aware of the problem with the onion cloud and are working on it so we should see some guidance or statement on this in due course. It's worth noting however that as this was never part of the original promise of onion this doesn't necessarily represent a priority - these are my words however not theirs!
There are many 3rd party platforms which allow you to integrate an Onion device with them and they may be more robust where management of multiple devices remotely is required - details on these services and how to get started using them can be found here - https://docs.onion.io/omega2-docs/connecting-to-cloud-platforms.html
I know the initial part of setting up one of these devices can be frustrating, especially if some of the above is not made clear, but none of this detracts from the large amount of amazing things which are possible with these devices.