To add filtering to event polling, go to the connector instance "Event Configuration", click on the icon to the right of “Configure Polling”, find the object you would like to filter and append your filter query to the “where” clause.

Example of filtering by OwnerId for accounts:

{"accounts":{"url":"/hubs/crm/accounts?where=LastModifiedDate>'${gmtDate:yyyy-MM-dd'T'HH:mm:ss.SSS'Z'}'&OwnerId='005f4000003cTOWAA2'","idField":"Id","datesConfiguration":{"updatedDateField":"LastModifiedDate","updatedDateFormat":"yyyy-MM-dd'T'HH:mm:ss.SSSZ","createdDateField":"CreatedDate","createdDateFormat":"yyyy-MM-dd'T'HH:mm:ss.SSSZ","updatedDateTimezone":"GMT","createdDateTimezone":"GMT"}}}