I am trying to do it via eBay sandbox UI (https://my.sandbox.ebay.com/ws/eBayISAPI.dll?MyEbay&CurrentPage=MyeBayMyAccounts) but when i clink on "Link my paypal account" button i am getting redirected to a page with the message: Http/1.1 Service Unavailable

Do i also need to add automatic payment method for my user?

Thanks.