Noticed IDPInitiated signon page is not loading by default in Adfs 2016 as it is loading in pervious versions.

Default IDP URL : https://adfsname.domainname.com/adfs/ls/idpinitiatedsignon.aspx
In my case, https://sts.windowstechpro.com/adfs/ls/idpinitiatedsignon.aspx

Ideally, in ADFS 2016 it is disabled by default.

Run the below command to see status of the IDP Initiatedsignon page.

Get-AdfsProperties | Select-Object EnableIdpInitiatedSignonpage

Now, To enable the IDP Initiatedsignon page run the below command,
Set-AdfsProperties –EnableIdpInitiatedSignonPage $True

restart the adfe service in all the adfs 2016 servers using the command

Restart-Service adfssrv
it can be done using services.msc as well.

It is all done, try to load the Idpinitiated signon page