I have a valid group id and I'm able to get the form template to create the case as well.

Sample request looks like this:

curl -X POST \
https://rms-world-check-one-api.thomsonreuters.com/v2/cases \
-H 'authorization: Signature keyId=\"----KEY-----\",algorithm=\"hmac-sha256\",headers=\"(request-target) host date content-type content-length\",signature=\"jdXff2WeThSX497msGivy6t7yPn3DU+MuGxArKs06no=\"' \
-H 'cache-control: no-cache' \
-H 'content-length: 593' \
-H 'content-type: application/json' \
-H 'date: Tue, 28 Apr 2020 23:36:34 GMT' \
-H 'postman-token: 925782ee-6902-7ee3-7dca-de6ca4e9c145' \
-d '{
"groupId": "<valid_group_id>",
"entityType": "ORGANISATION",
"providerTypes": [
"WATCHLIST"
],
"name": "Apple",
"customFields": [],
"secondaryFields": [
{
"typeId": "SFCT_6",
"value": "USA"
}
]
}'

Response :

There was an error connecting to https://rms-world-check-one-api-pilot.thomsonreuters.com/v2/cases