After WordPress updated to 5.5, our Access Anonymous Post Pro plugin created a PHP error. I had to disable the plugin in order for the site to load properly. Is there an update for the plugin?
You should try contacting the author of the item directly, they’ll likely be able help you far more than anyone here.
You can directly contact the developer of this plugin for technical support here: https://codecanyon.net/item/accesspress-anonymous-post-pro/9160446/support/contact