Help with Power BI Standard Gateway Connection to Postgres

Hi everyone,

I'm connecting to Postgres using Power BI Desktop with no problems (both from my local machine and from a Virtual Machine).

I also have a gateway installed in the VM, and thanks to it I'm able to schedule refreshes from Oracle with no problems.

I'm facing a problem when trying to refresh PBI Semantic Models (in the Service) which are using Postgres.

The error I'm getting is the following:

Data source error[ValidateMarkupTags]{"error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","pbi.error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","parameters":{},"details":[{"code":"DM_ErrorDetailNameCode_UnderlyingErrorCode","detail":{"type":1,"value":"-2147467259"}},{"code":"DM_ErrorDetailNameCode_UnderlyingErrorMessage","detail":{"type":1,"value":"[ccon]Please install Npgsql version 4.0.17.0</ip> or earlier.[/ccon]"}},{"code":"DM_ErrorDetailNameCode_UnderlyingHResult","detail":{"type":1,"value":"-2147467259"}},{"code":"Microsoft.Data.Mashup.ErrorCode","detail":{"type":1,"value":"10305"}},{"code":"Microsoft.Data.Mashup.ValueError.DataSourceKind","detail":{"type":1,"value":"PostgreSQL"}},{"code":"Microsoft.Data.Mashup.ValueError.DataSourcePath","detail":{"type":1,"value":"[ccon][ccon]<ip>XXX.XXX.XXX.XXX</ip>[/ccon]<ip><ip>XXX.XXX.XXX.XXX</ip></ip>;XXX[/ccon]"}},{"code":"Microsoft.Data.Mashup.ValueError.Reason","detail":{"type":1,"value":"DataSource.MissingClientLibrary"}}],"exceptionCulprit":1}}}

Any suggestions on how to install correctly Npgsql version 4.0.17.0?
I've tried from here https://github.com/npgsql/npgsql/releases/tag/v4.0.17 using the .msi but unsuccessfully. 

Thanks in advance