Did she only give you the shop/business's Instagram details? Not a personal one?
Or does she use it as her personal one?
It seems like a good sign that she's watched one of your stories and liked it (as long as it's her and not her colleague). But it's obviously still not definitive re. being romantically interested.
Do you chat to the colleague too? Is it likely to have been them?
I'm not clear on whether they're just trying to engage with customers and promote their business etc with the Instagram account she's given you, or whether one or both of them uses it as a personal account. The two of them sharing a personal account would be odd.
In any case, the asking for recommendations re. Berlin seems contrived to me. It's obvious that it's an excuse to have contact/make conversation (because the web id full of travel information and reviews, and people's personal priorities and experiences vary a lot ... so you'd get a much better/wider overview by just looking at trip advisor reviews etc.).
I suppose it's ok to do it (knowing that she will presume it is an excuse for contact).but I'd make it waaay less formal and wordy. If you do do that, if write a short and casual message, like;
"Hey xxxxxx, would you recommend Berlin? Been thinking of doing a trip there for a while".
That's it.
Keep it short, light, and casual.
It's more likely to illicit a response when someone thinks they can quickly write a casual line or two in response.
If she responds, you can add more info., like that you'd be going with a group of guys, and what you/the guys are interested in.
If you get into conversation, I would ask if she'd like to WhatsApp or something.. because I wouldn't be asking her out on a date on a work/business account.
I would make sure she's happy to have communication on a personal SM account/messaging account before asking her on a date.
Then I would just ask her if she wants to go for a coffee/or if she wants to join you doing something. I don't know what you do.
But it needs to be a public place for the first few dates. Also a good idea for it to be short.