Hello together.
Yes what Queeny said is right, it is better not to create own database with passwords and trying to generate some kind of an own login-system. Better is to use the already given options by wix.
But Queeny and me we have some kind different views.
I like more to go most possible CODING-WAY (oh sorry my CAPS again) 
.
Queen likes more to use as most as possible the given options provided by wix.
Both ways works → but it’s a question of flexibility. The more own coding you will implement into your site (CUSTOM-MODE) → the more flexible will be your site.
To say it in short —> Comparisson between → MAINSTREAM ← and → INDIVIDUALITY.
So maybe the best option is to find a mix of both. In your case it would be the best option.
You can install the Wix-Members-APP on your wix-site, which will give you even some more usefull options regarding the login and everything what is connected to it.
In my past i have done a lot of testing with the login and created also an own CUSTOM one.
You can search for those post for example searching for → “login + russian”, normaly you should get immediately some results like…
- Multiple Login light box forms - #2 by russian-dima
- Get User By Role - #12 by russian-dima
- and so on…
Normaly you need just to find one of my posts about login, because those are mostly all connected to each other. You can collect a lot about LOGIN in those posts.
But such own created LOGIN goes beyond every ordinary login.
You also can find much more simple ones using the search.