Free S2member - Creating/Using Custom Capabilities (CCAP)?

All,
I intend to use the FREE S2member (till I actually need the paid version).
Can you please point me to a URL which shares how to create custom capabilities and use them.

My usage is to have following types of products available to users:
Paid Access - The customer must pay via your preferred platform(s) (like PayPal, ClickBank, JVZoo, etc.) to access this product
Public Access - Anyone with the URL can access
Free Access 01 - Any registered user can access
Free Access 02 - User buys this product at $0 (the user shows interest in product)
a) Is it possible using FREE S2member or Paid S2Member or not possible at all ?
b) If possible, can you please suggest me some tutorial.
I tried to set CCAP for Free Access 01, but Paypal settings in S2member insists I provide some amount which has to be more than $0.

Thanks in advance.

See this: https://s2member.com/kb-article/video-custom-capabilities-for-wordpress/

Thanks Tim.
I will go through the URL provided by you.

Tim has pointed you in a good direction,

the issues you were having with PayPal is a PayPal thing, you will likely need to setup a 1 cent offer and that will satisfy PayPal

all the best,

Thanks Derrall,

Due to change in plans, I went in a different direction and could not spend time on what Tim Shared.
As now I am back, will be exploring the method(s) mentioned there & implement, if serving my purpose.

Without involving PayPal, can I ensure user (registered user or yet to register user) buys (just presses a buy button) without making any payment ? The user has to especially show interest in those products.
If above solution is already there in Tim’s link, I will spend good time on it in few days. If it’s not, could you please share some ideas ?