Hi @flpeSouza and welcome to the Community, it’s a pleasure to have you here!
Thanks for asking us!
I have found this similar post “Custom Objects & Associations API v4” where the solution from @LMeert might help you!
Also, I’d love to put you in touch with some of our Top Experts: Hi @Bortami, @HubSpot_Corey and @ChrisoKlepke do you have suggestions to help @flpeSouza, please?
Thanks so much and have a great day!
Best,
Bérangère
To get the correct association category and type id, you can view the API details in the UI (Settings > Objects > Associations) or by calling /crm/v4/objects/{objectType}/{objectId}/associations/{toObjectType}