@TalariB2this does not appear to be a Pega error. 

I am assuming you followed all the installation steps suggested in Pega Personal Edition v8.6: Postgre not able to connect on 5432  ?

The error indicates a problem with your Database.   

You may have this if you have an anti virus or firewall   blocking the "pg_restore" file, so please try to install after deactivating the anti virus software and turning off the firewall.    Have a look at this previous post,  this  post, this post, this post. and this post.

Please do a search for that error on the PostGres documentation:

https://serverfault.com/questions/260607/pg-dump-and-pg-restore-input-file-does-not-appear-to-be-a-valid-archive

https://stackoverflow.com/questions/35246737/postgres-tutorial-pg-restore-archiver-input-file-does-not-appear-to-be-a-val

https://tecadmin.net/pg_restore-archiver-input-file-appear-valid-archive/

As researched on the forum, I have most prominent cause for this could be due to the anti virus or firewall installed at your workstation. It is blocking the "pg_restore" file, so please try to install after deactivating the anti virus software and turning off the firewall.   

Hope it helps, kindly notify by marking this post as answered for larger Pega audience and tracking purposes.