It’s unfortunately more confusing than necessary. Possibly due to legacy reasons.
You need to charge your account and preload some money (note that these credits may or may not expire within 1 year). Then you may or may not need to cycle your API keys before things start working.
the /5$ refers to your theoretical monthly(?) spending limit, it doesn’t actually reflect how much money you have in your account. Note that this has historically been unreliable.
I hope this helps you at least get started, let us know if you run into any more hitches!
Thanks for your time and information, Please let me know if i purchase the plus subscription, will i be getting any developer feature for just testing API for free or still I have to add some funds to it and then only i can do testing.
hopefully you got my point.