I ran into this same problem yesterday on my desktop running Windows 8. After upgrading the OS to Windows 10, the problem is gone. Not sure if this will help you.
Also I did a search on the Web. The user JSBAIN on this forum posted the following:
"For those stuck on the activation step -- one thing that actually helped get past this step was to change my dns settings to override my router dns server with 8.8.8.8, or manually typing in your ISP's dns server.
I checked the logfiles found in C:\Users\[your username]\AppData\Roaming\Intuit\TurboTax\TY19\ErrorLog and found an error saying:
2020-01-17 20:15:34,283 [1] 2019.41.13.203 ERROR Intuit.Ctg.Map -
System.Net.WebException: The remote name could not be resolved: 'oauth.platform.intuit.com'
at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)
at System.Net.HttpWebRequest.GetRequestStream()
at Intuit.Ctg.Map.Net.WebResponse.GetPostResponseResult(Endpoint endpoint, String post, Encoding encoding)
This led me to try nslookup oauth.platform.intuit.com, which gave one timeout error before providing the address -- probably an error in the way my ISP has my router's DNS settings -- it takes one bad lookup before it gives the right answer. I think the TTAX activation software is not doing a retry, or just barfs on the timeout. Manually going to your network settings / adapter settings / Internet Protocol v4 settings, then under DNS, enter 8.8.8.8, or perhaps whatever your ISP's DNS server settings are. "
