What should be my approach towards selling a product that is developed for a particular industry?

Map the industry down to individual level. Talk. Verify your idea. Have a good pitch ready.

Regarding documents:
1. webpage with clear UVP and CTA
2. one liner for the "aha" moment
3. one pager pitch - number focussed.
4. three pager pitch - if the one pager was interesting.
5. blog posts, long content for people to dive in.

I wish you would have stated in your question what your monetization strategy is.

The answer will vary depending on whether you are selling to the talent, the hiring entity, or others (Maybe the talent schools? Casting agencies? Advertising agencies?).

The framework to answer each of these will be quite similar: Create a point of connection, outline the problem for that particular segment of the audience, present how your solution helps them, and then direct them toward the first Entry Point to your service.

In some instances, it will be advisable to include points to raise your credibility, such as testimonials, certifications, awards, etc.

More than glad to offer more specific help if you need it.

Your question is a little unclear. Is your customer an end user of your product or is your customer a company in the casting industry?

If a prospective customer (aka casting company) is interested in your product (aka knocking on the door), you need to start the conversation by qualifying your prospective customer and making sure that they are the right fit for your product. After you've qualified your customer and assessed that they are a great fit, you need to reinforce the value of your product and have the prospect confirm they understand the value.

Assuming you have figured out your pricing model, then you will go through the pricing numbers with your customer and if they agree, you can subsequently send an invoice and get paid for your product. Happy to go into detail about your sales process on a call.