I have same error when installing tapo plug. Tried from 2 different tplink accounts using a tapo plug in each. Works from tapo app using the different accounts and can see and use tapo plug in each. When using homey app official and log in either account says too many requests. When I uninstall official and install the second app unofficial, and type in log in details, says 404 error, using either login. Starting to think that it may be tplink server issue.
We are waiting on Tapo to change the rate limit on their side. In the mean time you can try the test build v1.0.5 where the state update of the devices isn’t polled from the API anymore to reduce traffic.