User Provisioning API for creating users in a group

I’m a newbie in NextCloud API’s and I have an issue when creating a new user from a Group Admin account. I make the POST call with “userid” and “password” fields and it throws this error:

“ocs”: {
“meta”: {
“status”: “failure”,
“statuscode”: 106,
“message”: “no group specified (required for subadmins)”,
“totalitems”: “”,
“itemsperpage”: “”
“data”: []

I’ve tried to put the “groupid” field in the POST body, in headers, in the URL…nothing works!!

Please I need help with this issue. Thanks in advance!