No, it's a bit different.
First off, i would suggest making a back up of the site and the power store database.
then delete all of the power store files and folder, except for the connection folder.
Next copy all of the php files and folders from the power store zip file you downloaded into your poser store site.
Next copy the install/webassist folder form the power store download into the root of the power store site.
then run the install/scripts/v3_v4_update_script.sql file on the database