"You have not been online in the last 30 days. Please start the game while online to check for any login agreements."
Generally, this is a connection issue if the steps above don’t help. The game can’t reach our servers due to a block or unstable connection. Try our connection troubleshooting located Here. I would not change the system’s clock; that doesn’t sound like it was a solution for you, either.
If the issue continues, from here two advanced troubleshooting steps. Try to see if a cellular hotspot bypasses your home network equipment and ISP. A VPN can be used to change the route and see if either help temporarily fix this issue then we narrowed down the source from the PC to the network or route the connection is taking. The Internet Service Provider can help look into this from here.
Thank you.
Copied word for word from the official Diablo II: Resurrected forum. Read the whole thread — and reply — on us.forums.blizzard.com. Get an alert for the next one