Unable to set permissions on a google drive folder

Not sure if it is the best way, but what you can do is use Make an API call to do this,

In Make an API call use,

URL : /v3/files/{{16.id}}/permissions

And, Request Body will be,

{
    "role": "writer",
    "type": "user",
    "emailAddress": "‘validgmailaccount@gmail.com"
}