For app development startUp do I have to have legal company papers if am going to lunch an app like airbnb etc ?
If you are going to lunch app, maybe you should do breakfast first
No you don’t, however, you won’t be protected and neither will your ideas. You should probably look into patents and confidently agreements with anyone you’re working. Maybe potentially non compete agreements depending on the type of work and how specific it is. If I was you I’d seek legal advice from an attorney who is well versed in Intellectual Properties.
Obvs
Do u know what kind of papers exactly and where I can start ?
No - talk to a lawyer, I can’t give legal advice - but I did an LLC, then I think you need to submit a business plan and any patents associated with that. If your idea is good - get legal advice first.