Using 1 PW for years, one hospital site problem. need help

when I try to log into a specific hospital site using 1PW (I do get medical care at this hospital), I get something from “Microsoft Server” showing me an icon and I can’t get into the site to see my info. this just happened recently. I can access the site using Alfred or even DuckDuckGo but not using 1 PW - have tried to fool 1PW using different logons etc…with my same password etc…but I can’t seem to fool the “Microsoft Server” - I don’t know where it (the Server) came from and everything I read, tells me not to get rid of it. Any thoughts would be appreciated. thx - Whoops, just tried it again in 1 PW using Safari to get to 1PW instead of Firefox and the log in worked without showing me that stupid Microsoft Server icon. Very strange…???