error 403 is forbidden, which is typically a proxy error. Make sure your private proxies that are linked to your moz accounts are good.
429 is an object creation error, which is an odd error.
It sounds like maybe something 3rd party is acting upon the addon. So set the entire addons folder (which is inside your scrapebox folder) as whitelist in all security software such as anti-virus, malware checkers, firewalls etc.. and then try closing down any unneeded programs.