Hello Sudigital, this problem seems to be realted with server permissions, I suggest you to use an FTP client like filezilla and check that.
This is a good gide to follow:
https://www.malcare.com/blog/wordpress-file-permissions/
also, it may be cause by a plugin, this are a few steps to check:
1 – Deactivate all plugins that are installed on your WordPress Site.
2 – Re-activate one of the plugins on your list.
3- Visit the site to see if the 403 error is being displayed.
4 – Repeat steps two and three until the 403 error is shown. This is the plugin that is causing the problem. You may need to change its configuration settings or remove it entirely.