You cant. They just shut down the server and removed the unlocker app from their site. Maybe, just maybe, they will release a “rewritten version” in the coming months according to some guy on xda who asked them.
This shit is the last asus product Im buying for a loong time if ever.
There is no info on zenfone 8 and 9 as they conveniently left that out. There is no APK on the download page for zenfone 8 or 9, neither can you use the APK already downloaded. See one of the newest XDA threads on Zenfone 8.