I have the same issue. I click login and then the sales addin pane changes to “logged in?let’s go”
A new window opens and it allows me to select the correct Hubspot account, it shows it is succesfull in the end and closes automatically. The minute it closes the sales addin pane changes to “login” again.
I have followed all solutions found on hubspot knowledgebase like, enabling third party cookies, clearing browsing cache, etc but it still does not work. I also tried with Edge and it did not work.
I use a free hubspot account along with Microsoft 365 Basic, and Outlook online. From what I have understood this combination should work.