If you're encountering the "document is not defined" error even after installing Flowbite, here’s what you can do: Check angular.json:

Ensure Tailwind CSS and Flowbite are properly configured in your angular.json file.

Example configuration -

Check to Tailwind is Configured Correctly. After run ng serve.

Since I am new to this, if I have said something wrong or if anyone can explain my mistake, I will humbly accept it. Thank you.