Hi @fxholl, as a first step you might want to update your n8n version, as more recent versions would take the sunsetting of API keys into account.
When creating a private app in Hubspot, make sure you select all relevant scopes (HubSpot - n8n Documentation has a list). At the end of the process you get a token like so:
This token can then be used in n8n by selecting the “App Token” (instead of “API Key”) authentication on the Hubspot node:
