I need the user to go through a log in process

I have everything working correctly.
Last item I need help on.
I have 4 Forms which need to be secure. What I mean is I need the user to
go through a log in process to insure I don't have unauthorized people
using the form or viewing private data. How do I accomplish this.
The sample form I made. Anyone knowing the link can open it.
I will 3,500 authorized club members accessing these 4 forms. Hope to add
additional forms later on for the club membership.
Thank you for your time,
Steve C.

We don't have a membership feature here in JotForm. However, you can create a condition wherein all fields will appear if the correct value is entered in the field. Please take note we don't normally recommend this option because there is a chance that your account will get suspended if you are using words like (passwords, access code, code). If that happens, let us know so that we can re-activate your account.

I created a demo, please check it out: https://form.jotform.com/62764534893973. 

You can clone it or create a new form by following these steps:

1. Create a Text Box field.

2. Create your registration form below the "Club Given Number" field.

3. Click the Conditions button in the toolbar. Choose the Show/Hide Field condition.

4. Create a condition wherein if the value "12345" is entered in the "Club Given Number" field, all fields below will appear. To select multiple field as shown in the screen animation below, press CTRL while selecting the fields. 

Do this conditions on all four forms. 

Hope that helps.