Create CI4 project in sub folder

Hi ! 

I did several research about this subject, but I didn't find a solution.

I have a a domain who contains several projects. For example, I have something like this :

• https://example.com/project_one/
  
• https://example.com/project_two/
  
• https://example.com/folder/project_three/
  

Each project has a new folder (it'is a website used for development experimentation).

Now, I have tried to create a CI4 project inside a folder, like my other projects. So I put my CI4 folder (with /public, /app, /writable, etc.) inside a folder like :

• https://example.com/folder/codeigniter_project/
  

I want to access my project from this URL, without the index.php and without the /public folder in the URL.

I think I need to create a .htaccess file at the root of the project to redirect to the /public folder (and to adapt the .htaccess file inside the /public folder), but I can't get it to work...

If I don't have a .htacces in my CI4 root folder, I have a 403 Forbidden message, and if I create a .htaccess file, I always have a 500 error.

Someone knows how to do that ?

Thanks a lot !