i'm brandnew here and hope, that the posting is at it's right place. if not, please be propitiate to me

today i got an original cd-rom, sealed and bnib (!!!) of uo2a (made 1999) with a sticker on the case, telling me a retail code for activation via following link : https://ultima-registration.com .
however the site is not available and so i want to know, how to do it 'today' (over 10 years later^^).
do i need to download and install the client software as well ?
i have no idea how to do it, so any help is appreciated. thx to anyone for help.
best regards nayss