First off, what country are you in? We recently had to add additional countries to our list of blocked IP addresses to comply with US law, so if you’re trying to connect from, say, Russia, you wouldn’t be able to.
Assuming that’s not the issue, you can try manually creating a token from Cesium ion. You can find this in the Access Tokens tab on Cesium ion. Once you have the token, you can copy it and paste it in the token window like so:
Please let me know if this helps!