Problems with activating Plugin datasource_rdspostgres

[pk1nzl]

Hi, i have following error when trying to enable the postgresplugin in checkmk.
We use Version 2.3.0p21

Can you help?

Thanks!
Regards Philipp

[pk1nzl]

I fixed the issue with this site:
https://forum.checkmk.com/t/special-agent-for-postgres-rds-is-not-working-in-2-2-p9/41332

But how can i activate the Check?
I added the Rule and provided Username and Password, but how does the check know how the rds instances are named?
Do i have to add the name of the aws instance at the explicit hosts?