My feedback:

Clarification questions. You forgot to ask about the business model. Do they have stores? How many? Which type? Do they sell to distributors? What type of products do they have (premium, sport comfort, etc).

Structure. This buy-the-book structure can be good only for people who didn't spend a single day in consulting like Cosentino or that have been analysts like Cheng. 
I've never seen a consultant talking about 3Cs. You should segment revenues (existing and possible ones): on 

• existing stores (how do we operate them?)
• new stores in existing markets (how do we operate them?)
• third-party stores in existing markets
• new markets (though stores and/or distributors)
• new revenue streams (e.g., licensing, sport consulting, apps, etc)

For existing stores you can talk about volumes of customers, increase of spending on each receipt through price increase, new products, etc.

In discussing prices and how to increase volumes you can cover competition, competitive advantages, store location, product type, etc. 

The issues with these structures built on buckets instead than on business cases/business plan structure are that they are disconnected from consulting reality, unspecific, and you collect pieces of info that you then lose or you cannot attach to drivers connected to the end goal.

To be blunt, this is NOT a good structure:

- It seems like a list of random things you collected and tried to somehow categorize them meaningfully. This has nothing to do with rigorous top-down thinking.

- Even now looking at it, it is still not MECE (e.g. current products - placement of products in the store).

- No need to ask these clarifying questions. For example, if the interviewer says „No, we wanna stay in country X“, then you cannot bring the point „geographical expansion„ in your structure anymore, whereas if you do bring the idea, you already got a cookie point for being creative (the interviewer might very well comment that it is out of scope, but you couldn‘t have known that).

It is pretty clear that they want to grow and by how much, so your first task is to lay down ways how to grow, and then discuss with the client which ways to prioritize based on impact, feasibility and risks. You should lay them down in a structured manner, but tailored to the case (so that the interviewer does not think that you are simply jotting down theoretical frameworks your learned by heart).
 

I would structure it for example this way:

We can grow either

A) Organically

B) Anorganically (e.g. acquire smaller sportswear firms)

A) Organic growth can be achieved by:

1) Strengthening the existing business

2) Exploring new business opportunities

Ideas for 1)

a) Improve existing sportswear products (design, durability, function etc.) and/or optimize product mix; we can determine relevant KPC and NPS by in-store or digital customer surveys (e.g. by providing a lottery as an incentive)

b) Improve prices; we can determine optimal price point by competitor benchmarks, customer surveys, market reports etc.

c) Marketing optimization (e.g. leveraging customer data for SEO or targeted mail/email advertising, sponsoring through sports events, campaign through Instagram influencers, TikTok brand videos etc.)

Ideas for 2)

a) Geographical expansion (e.g. USA, maybe under a new brand)

b) Expansion into adjacent clothing markets (e.g. uniforms)

c) Additional revenue streams (e.g. in-store print service to have the name of your favorite player on your football jersey, shoe repair service, sports snacks and beverages, in-store cafe, white label service)

d) Additional distribution channels (e.g. online-channel, second-hand shops)

e) Additional product categories (e.g. childrenswear, accessories)

(edited)