I just saw the edit including mention of Safari. I don't have a mac or safari, so it "could" be an issue there, clear your cache if hivesigner gave you weirdness but my system only relies on sending you there, getting back the confirmation token that you logged in to them ok, and then it doesnt rely on cache or anything, it just keeps a cookie that you are you and you got logged in ok at hivesigner, it wont need to do anything else with any external stuff till you were to try a chain operation like using money from your wallet to send a tip, then it would use the hivesigner token to say, is this still good? But none of that cares if you are using safari, a phone, a fax machine or a potato, it just sends a link to the web, gets an encrypted yes or no string back and moves on, no magic there.
I will have to find someone with safari and a mac to try it and see if it seems related to any of that. Safari is kind of famous for being shitty to web developers. Its sort of the Apple version of Internet Exploder (MS Explorer) which is also famous for being absolutely useless.
Chrome however should have had no problem. sounds like maybe by messing with hivesigners login denial, and trying various browsers, you got your tokens in a wad, and need to clear browser caches, clean up your login issue at the hivesigner side and it would all work out fine. I expect,and hope anyway