This is because ckan has a bug when searching for date field which the team has raised.
ckan/ckan#4130
Once this is fixed the ckan query in the provider can be updated in this file
packages/lintol/capstone/src/CkanResourceProvider.php
Some thing like this is an example.Change it having variables for format and date.
$ckanData = collect($this->ckanClient->ResourceSearch(['query' => 'format:csv', 'query' => 'date:2018-03-03'])['result']['results'])