Are you talking filesystem?

If so the easiest way to do this would be to have both sites on the same machine and check you have the correct permissions for the user accessing the files

I'm not talking about filesystem. I have both website on the same server. I have two laravel websites like this:

/public/website1

/public/website2

I need access to this folder to see upload files and if is possible, uploading from website2.

Well, thinking about it, if your /public/ directory is publically accessible, you should be able to access the content. So, what I would do is:

Build a small RESTful api for site1 and then use this api from site2 to both fetch from and upload to site1.