Sysadmin How to add SSH/FTP user? is it SSH user and FTP user is not same?

I just create a vhost domain and get FTP user like information below:
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FTP hostname : 88.88.88.88
FTP port : 21
FTP mode : FTP (explicit SSL)
FTP Passive (PASV) : ensure is checked/enabled
FTP username created for test.virtual.com : test01
FTP password created for test.virtual.com : Testing2016
-------------------------------------------------------------
I try to login with FTP client like FileZilla/WinSCP and it works.
I usually access my SSH on command below :
ssh root@88.88.88.88
(then write password then tadaa it works fine.)
but when I tried with FTP username and password
ssh test01@88.88.88.88
or
ssh test01@test.virtual.com
it will return "test01@test.virtual.com's password:"
when I enter the password then it will return :
"Permission denied, please try again."
I already make sure the password is right.

---

and how can I change the permission if I can access it on ssh?
So I usually create git hook on root. (so i can make remote git remote add root@88.88.88.88:~/git-repo/test.virtual.com.git) and hook it to public folder of domains.

and now I need to create git for someone that I can't give root access and password
So I think I can put git hook on "private" folder or something new folder of domains folder.
and give him FTP username and password
so they can access git hook like "test01@test.virtual.comits already on domains folder)/private/git/something.git"
and hook it to "test01@test.virtual.comits already on domains folder)/public/"

The Summary of my question is:
1. Is it FTP username and SSH username is not same?
2. If its not same How to create SSH username? And Permission so I can access it like story above
3. If its same why I can't access when I enter right username and password?
4. Can I make git access like that I tell on last paragraph?