Your request to the UMA resource registration endpoint is invalid. Please try below given request.

curl -v -X POST -H "Authorization:Bearer a804d0e8–2f9a-3bea-b595–41742a8aac19" -H "Content-Type: application/json" -d '{"resource_scopes":["view", "download"], "name":"Photo Album"}' https://192.168.1.20:9443/api/identity/oauth2/uma/resourceregistration/v1.0/resource -k

Also, make sure to send a valid PAT as the bearer token of the above request.