Failed to find any class that implements Connector and which name matches io.aiven.connect.jdbc.JdbcSinkConnector

Question

I want to ingest data from kafka to postgres for which i have to connect kafka and postgres.I have used io.aiven.connect.jdbc.JdbcSinkConnector.My standalone.properties file is given below:

rest.port=8084
bootstrap.servers=localhost:9092

key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=false
value.converter.schemas.enable=false

offset.storage.file.filename=/tmp/connect.offsets
offset.flush.interval.ms=10000

plugin.path=/usr/local/share/java

Below is the jdbc- sink connector file:

name=example-jdbc-sink

# These are defaults, but they're here for clarity:
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
value.converter.schemas.enable=true

connector.class=io.aiven.connect.jdbc.JdbcSinkConnector
connection.url=jdbc:postgresql://localhost:5432/advicedb?user=**&password=***

topics=messages

# This is default, but it's here for clarity:
insert.mode=insert

Now the problem is when I am running the connector with the command bin/connect-standalone.sh config/connect-standalone.properties config/jdbc-sink.properties it is giving the following error:

ERROR Failed to create job for config/jdbc-sink.properties (org.apache.kafka.connect.cli.ConnectStandalone:107)
[2022-02-10 15:15:05,764] ERROR Stopping after connector error (org.apache.kafka.connect.cli.ConnectStandalone:117)
java.util.concurrent.ExecutionException: org.apache.kafka.connect.errors.ConnectException: Failed to find any class that implements Connector and which name matches io.aiven.connect.jdbc.JdbcSinkConnector,

I have checked the path, the files are on the right directory but its still not working. i have java version 11 and ubuntu 20.04