It is a known issue in previous version of Toolset Access plugin, please try to upgrade the Access plugin to the latest version 2.8.2 and test again, you can download it here: https://toolset.com/account/downloads/
Luo is on Vacation. This is Minesh here and I'll take care of this ticket. Hope this is OK.
I checked on my local test install and I can set the permission to the guest users so that they can access the user form on the frontend. It works just fine.
Can you send me admin access details so I can review your current setup and investigate further.
-- Please share the problem URL where you added the user form.
*** Please make a FULL BACKUP of your database and website.***
I would also eventually need to request temporary access (WP-Admin and FTP) to your site. Preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed.
I have set the next reply to private which means only you and I have access to it.