Hypixel (a major Minecraft server) bans many utility clients. You must verify on Hypixel’s “Allowed Modifications” list. If Arial-Client includes auto-clicker or aim assist, it is banned.
This is an unusual prefix. In many cases, users encounter a file simply named Arial-Client-1.8.9.zip . However, the inclusion of suggests one of the following: File name- Arial-Client-1.8.9.zip