Get the unsigned chain-specific message needed to be signed by the wallet owner using the wallet private key

curl --request POST \
  --url https://app.dynamicauth.com/api/v0/environments/{environmentId}/nameService/{chainName}/signingMessage \
  --header 'Content-Type: application/json' \
  --data '{
  "address": "0xbF394748301603f18d953C90F0b087CBEC0E1834",
  "domain": "An example name",
  "uri": "<string>"
}'

{
  "unsignedMessage": "<string>"
}