Yes Elly. You are correct. Thanks for indicating the wrong information which is mentioned in solution documnet.
Wrongly I have seen system name as "PRPC" which is nothing but server name. And same time solution document also has PRPC:Browser requestor type screen shot. That is the confusion.Thats why I didn't peroperly verify system name when you asked initially to update PEGA:Browser requestor type.
Now I got below system name for LSA 7.1.7 and 6.2 exercise system
I have updated browser requestor type at both system as ber above mentioned system names. Now I can able to complete the SSO lesson exercise.