Won't copy Phpbb 3 forum files

Hello everyone. The question is that in the last step it tells me that it cannot connect to the / files folder.
I have changed the CHMOD permissions to 777 and it does not allow copying.
I don't know how to check if the htaccess is blocking me, since I don't know how to check it.
I'm from phpbb 3.1.3 with MYBB 1.8.

The MyBB Merge System encountered the following problems:

• The directory could not be read. Please adjust the chmod permissions to allow it to be read from and ensure the URL is correct. If you are still experiencing issues, please try the full system path instead of a URL (ex: /var/www/htdocs/path/to/your/old/forum/uploads/ or C:/path/to/your/old/forum/upload/). Also ensure access isn't being blocked by a htaccess file.
  

Greetings and thank you.