JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
We don't have any reported issue regarding Google Drive integration. I tried it myself and I was able to integrate one of my forms. There are no problems in regards to the authentication.
Since you said that you were able to authenticate in Google Spreadsheets then I assumed that you are not having issues with the login credentials.
Please try using another browser to see if it will work or not. It is possible that you are logged in to a different Google account in the same browser where the Form Builder is.
I would recommend signing out all Google accounts first. After that, please logout from JotForm and then log back in again. Please try the integration and check if the authentication will be successful.
Let us know if you still can't authenticate in Google Drive. Thank you.