[URGENT] Any up to date guide for configuring SSO ?

Dear Experts,

does anyone has an up to date document on how to configure SSO for ABAP systems on RHEL ?
We need to configure this VERY urgently! I have done this many years ago and several older
guides are not helpful. Our Unix and Windows specialists suggest, that the SSO setup which I have
performed is using older protocols, which are being ignored by current operating systems.

Many thanks!

NB: The error which we are getting is: Can't find client principle <user>@<domain> in cache collection.

Any help would be much appreciated!