I am installing Pega-8.1 on AWS EC2 instance with Tomcat and Postgresql as the configurations. While performing the build step, I have been running into the below error, I remember having the similar problem while creating a Pega-7.4 server as well. The user I created has super user preveliges, all preveliges on DB and schemas listed below. Am I missing on any settings, Can someone share potential reasons for the error and solution?

Error -

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Monaco; color: #f2f2f2; background-color: #000000} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Monaco; color: #f2f2f2; background-color: #000000; min-height: 14.0px} span.s1 {font-variant-ligatures: no-common-ligatures} Buildfile: /root/PEGA_8.1/scripts/setupDatabase.xml
install:
Initialization:
[echo] Performing Install Finalization
[echo] Using logging configuration from: ./config/deploylogging.properties
[delete] Deleting directory /root/PEGA_8.1/scripts/taskRuntimes
[mkdir] Created dir: /root/PEGA_8.1/scripts/taskRuntimes
[delete] Deleting: /root/PEGA_8.1/scripts/logs/Warnings.log
[pega:propertyparser] Reading Properties from: /root/PEGA_8.1/scripts/setupDatabase.properties
[pega:propertyparser] pega.jdbc.driver.jar=/opt/tomat/lib/postgresql-JDBC.jar
[pega:propertyparser] pega.jdbc.driver.class=org.postgresql.Driver
[pega:propertyparser] pega.database.type=postgres
[pega:propertyparser] pega.jdbc.url="jdbc:postgresql://127.0.0.1:5432/DB-81"
[pega:propertyparser] pega.jdbc.username=dbadmin
[pega:propertyparser] pega.jdbc.password=*****
[pega:propertyparser] pega.admin.password=*****
[pega:propertyparser] rules.schema.name=pega81_rules
[pega:propertyparser] data.schema.name=pega81_data
[pega:propertyparser] customerdata.schema.name=
[pega:propertyparser] user.temp.dir=
[pega:propertyparser] pega.zos.properties=
[pega:propertyparser] system.name=pega
[pega:propertyparser] production.level=2
[pega:propertyparser] multitenant.system=false
[pega:propertyparser] update.existing.applications=false
[pega:propertyparser] update.applications.schema=false
[pega:propertyparser] automatic.resume=true
[pega:propertyparser] pega.jdbc.driver.jar=/opt/tomat/lib/postgresql-JDBC.jar
[pega:propertyparser] pega.jdbc.driver.class=org.postgresql.Driver
[pega:propertyparser] pega.database.type=postgres
[pega:propertyparser] pega.jdbc.url="jdbc:postgresql://127.0.0.1:5432/DB-81"
[pega:propertyparser] pega.jdbc.username=dbadmin
[pega:propertyparser] pega.jdbc.password=*****
[pega:propertyparser] pega.admin.password=*****
[pega:propertyparser] rules.schema.name=pega81_rules
[pega:propertyparser] data.schema.name=pega81_data
[pega:propertyparser] customerdata.schema.name=
[pega:propertyparser] user.temp.dir=
[pega:propertyparser] pega.zos.properties=
[pega:propertyparser] system.name=pega
[pega:propertyparser] production.level=2
[pega:propertyparser] multitenant.system=false
[pega:propertyparser] update.existing.applications=false
[pega:propertyparser] update.applications.schema=false
[pega:propertyparser] automatic.resume=true
[pega:propertyparser] pega.jdbc.driver.class=org.postgresql.Driver
[pega:propertyparser] update.existing.applications=false
[pega:propertyparser] pega.jdbc.password=*****
[pega:propertyparser] update.applications.schema=false
[pega:propertyparser] automatic.resume=true
[pega:propertyparser] pega.jdbc.driver.jar=/opt/tomat/lib/postgresql-JDBC.jar
[pega:propertyparser] rules.schema.name=pega81_rules
[pega:propertyparser] pega.jdbc.url="jdbc:postgresql://127.0.0.1:5432/DB-81"
[pega:propertyparser] pega.database.type=postgres
[pega:propertyparser] user.temp.dir=
[pega:propertyparser] production.level=2
[pega:propertyparser] pega.zos.properties=
[pega:propertyparser] customerdata.schema.name=
[pega:propertyparser] pega.jdbc.username=dbadmin
[pega:propertyparser] pega.admin.password=*****
[pega:propertyparser] multitenant.system=false
[pega:propertyparser] system.name=pega
[pega:propertyparser] data.schema.name=pega81_data
[echo] *** JVM Arguments -Xmx1280m ***
[pega:hasenoughspace] Found 27844224KB of free space on '/tmp'
[echo] setting to generated ddl
[echo] Driver Path: /opt/tomat/lib/postgresql-JDBC.jar
[mkdir] Created dir: /tmp/PegaInstallTemp-13-November-2018-16.46.44/load
[mkdir] Created dir: /tmp/PegaInstallTemp-13-November-2018-16.46.44/pr_temp
[touch] Creating /root/PEGA_8.1/scripts/logs/Warnings.log
[echo] Using /tmp/PegaInstallTemp-13-November-2018-16.46.44 for install scratch space...
[unzip] Expanding: /root/PEGA_8.1/archives/prweb.war into /tmp/PegaInstallTemp-13-November-2018-16.46.44/load
[unzip] Expanding: /root/PEGA_8.1/archives/pegadbinstall-classes.zip into /tmp/PegaInstallTemp-13-November-2018-16.46.44/load
[copy] Copying 1 file to /tmp/PegaInstallTemp-13-November-2018-16.46.44/load/WEB-INF/classes
[copy] Copying 1 file to /tmp/PegaInstallTemp-13-November-2018-16.46.44

Checking Configuration Files:
[echo] Rules schema has been set to 'pega81_rules'
BUILD FAILED
/root/PEGA_8.1/scripts/setupDatabase.xml:471: The following error occurred while executing this line:
/root/PEGA_8.1/scripts/setupDatabase.xml:1451: Unable to load driver class from the following path(s): /opt/tomat/lib/postgresql-JDBC.jar