I'm having the same problem as described in this thread:
I don't have a solid blue light. The light on my unit is green, however whenever I try the registration process, after logging in I'm redirected back to my hub's homepage, but it still isn't registered. Any chance there's an easy fix for this?
I don't see "Emails Linked to this Hub". I see "Register Your Hub. Please register your hub to use the Hubitat Mobile app and cloud services. Create an account or login if you already have one. After login, you will be redirected back to your hub."
Check your network to make sure the hub can connect to the cloud and that your router's firewall settings aren't blocking the hub to access the internet. You can also send me a private message so I can confirm if your hub is reaching our server.
Make sure your hub is using DHCP, instead of a static IP address. The best practice is to reserve an IP address for the HE hub in your router’s DHCP server.
This worked for me. I already had a static IP for the Hubitat on my router, but I also had the Hubitat set to static IP. Changing it to DHCP and rebooting allowed it to register.