Add New Plugin Error

I’m so frustrated at the moment. I cant add new plugins after a fresh installation of WordPress in order to restore my backup. The site was up-and-down with wordpress errors for the last 2 weeks already and now I can’t do anything further to just restore my old site. Very disappointing.

I did full reset through CPanel and FTP and nothing seems to resolve the problem.

Does anyone else have these issues?

The page I need help with: [log in to see the link]