it probably exploited a passive service you had running. possibly your minecraft hosting software, but its just a guess
i can really only think of three likely ways it got onto your server assuming you didnt share the logon credentials or use sketchy programs - vps used outdated service packages, mc server was exploited somehow, or the physical machine your vps is on got hit and it affected all virtual machines on the server.
theres more ways it could have happened but these three are the most likely afaik. you’re gonna have to get them to wipe your vps completely and make a new virtual machine, and this time keep everything up to date