users endpoint lets you manage your company’s users. You can:
GETa list of all users in your company, including each user’s ID, email address, full name, and profile picture URL.GETa specific user by their user ID.POSTa request to change a user’s access to your company or to specific sites.
company_id from MyKinsta > username > Company settings > Billing details.
The company_id is also shown in the URL in MyKinsta, for example, in the URL https://my.kinsta.com/?idCompany=bdd25d71-5706-4890-870f-1adda17c505d the company_id is bdd25d71-5706-4890-870f-1adda17c505d.