I recently signed up to try out HubSpot. I would get to the last step and then I would get an error message about changing my browser's settings to allow cookies. This was not enough to help me. My browser allowed cookies but my browser extension/add on was stopping HubSpot. Turing off the security (I'm not sure if it was uBock Origin or Privacy Badger) enabled HubSpot to complete the sign in process.
I recommend adding text to the effect that browser security should be set to allow HubSpot cookies will be helpful to others like me who have installed and "forgotten" as blockers and privacy tools. It should be obvious that the extensions/add ons are the issue, but I followed your instructions which did not resolve the issue.
