What do I have to do to get a proper reply from?

Allright, personal thoughts about the shots shown.

Yea, the rocks on the firepit could use a little bit of re-uving and perhaps a texture change, would be easy to do. (and easy to mention)
Some of the non-burned wood seems a bit stretched, also something easily solvable.

The tents look fine, same with the chairs and bags, but i’d need to see up close if there is a detail normal and if they look fine up close.
Some good micro detail on those would go a long way.

For the cranes one could ask that it requires high end textures for each part and piece, and in general it would potentially help… but you cannot expect a massive crane like that to have each piece a separate texture.
some rust here and there would make it look great up close.
The reflective value looks a tad off, cant put my finger on it, but simple value-tweaking would go a long way.

Would I personally refuse the pack?
Its hard to tell, I like to be up close and personal, I would def. suggest to tweak some things.
I’d like to see the rocks re-uv’ed and perhaps have a more proper texture (/rough/norm) id like to see some of those branches/wood to be less stretched (which is an official reason for declining content)
I’d like to see the tents/bags up close and make sure there is micro detail so it really comes across as tent fabric canvas.
I would try and give the cranes a more realistic texture (smore rust/damage) and use an atlas to easily add some variation to parts.
I would probably not decline the cranes, but again… its sometimes really hard to tell without actually being able to look at the models in real time.

I can also not say anything about the material setups/blueprints, I do know that the people that look at the blueprints can be real whiney about even one overlapping wire and everything needs to be over-explained inside the blueprints.
I can also not say anything about the use of material instances and other “behind the scenes” content.

Its all minor and small things at first glance, stuff that can easily be rectified.
If I where i’d spend some time improving the content a little and resubmitting.
Perhaps ask on a forum thread/facebook post/discord channel what could be improved.

And I’d also suggest him to not give up on this yet.

But I also do understand that the marketplace is overwhelmed with content, so I can understand that there are instances where you just have to be bold and send a generic response.
If you get a few dozen packs a day, its tedious and time-consuming to tell every potential seller whats wrong, and even worse if you’d need to explain not only what needs to change but how to change it.
I doubt they’d get paid for telling potential sellers how to make their content and how to improve it, and while I do feel like they should give guidance to sellers who show great potential but just have a few things wrong… I also feel that if the content is below a certain bar they need to have the right to send a semi-automated mail with “lol, nope”.

In this case an email with “retexture rocks, check your uv stretching/texel density” would have gone a long way. and would have taken less time than reply to any of us in this thread. (something to consider in the future)