Adding a simple log in page

Hello,

Im new to wordpress so i’m not even sure if Im posting this in the right place, but here goes.

I want to add a page (which Ive done) for a clients. Just a simple log in, even just a password for clients to access various forms to fill in and submit.
The content I can deal with, its just the log in bit.

I know there is a password protect page but there is no way to customise it with the theme Im using (Brooklyn

The sort of think Im looking for is like this

So nothing fancy, literally just a password to page that has some content in.

Is there a plug in or something that could make this easier?

I dont need the whole account thing, just a password would be fine!