ok one more thing, before trying to register the sim and while having all the other nics disabled in control panel (and having restarted simulator after that) goto settings, and connect to a fake a wifi connection, perhaps even create a new connection, the password for the connection is always the same as the name / SSID. i just noticed in the thread i had posted here Simulator can bind itself to wrong network adaptor (on windows) making registering the simulator always fail - #7 by joyrider3774 that it sometimes would still fail to connect if i did not do that.
On the other hand is there any reason you want to register the sim ? Registering a sim is only needed if you want to use the score board api which only season and catalog games can do. Another reason is to simulate the process of side loading as it would work on the playdate using the accounts page. But this is not really needed for development, as you can just copy the pdx directory to data disk and the simulator when choosing upload game does the same