Hello,
My name is Dhrumit and I am the developer of Groundhogg Booking Calendar Plugin. I installed Forminator and groundhogg calendar plugin and I am able to recreate this issue successfully. I think there is a conflict during the authentication process.
I can send you a developer copy of our plugin. You can contact me on my email address [email protected] for development copy.
I hope we can sort this issue out.
Thanks!