I think you need to consider where you want to store the data. At this point, I will discourage you from using traditional file services. It has a lot of baggage, including the need to have a "server" device that is always on, maintaining a user directory and passwords, implementing a VPN to allow authorized connections only, possibly a dynamic DNS service if you have a residential service, creating a backup, and the lack of true collaborative access to the files. You do not define the nature of your business so I have no context on what apps/documents you use. However, I generally discourage content creative workflows from using traditional file servers as the Adobe products are not supported with file sharing solutions. And if you are doing general office productivity (Microsoft Office), then Teams site and the Microsoft cloud will provide you with a great set of features, including collaborative file access, versioning, and FileProvider support for local caching on the Mac. If you are a Google shop, then look at creating a shared folder that everyone has access.
Start by considering who you are using for email. As a business, you are likely using Microsoft or Google as your mail provider. If so, they both offer cloud storage solutions that lend themselves very nicely to small businesses. And, in may cases, their base offering is often enough space that you do not get an upcharge. By using a cloud storage solution, you don't need to build a VPN, create a server, or build/maintain a backup. This allows your users to work from anywhere and have access to the data without jumping through hoops.
Also, by moving your storage to the cloud, you don't have to worry about any limitations with your internet service. If you are working off a residential line, it is likely that you have an asynchronous service (assuming you are in the US) and likely have a dynamic address, making remote connections a moving target. This means the download speed may be fast but upload is slow. This can make your VPN users very frustrated. By moving your data off your LAN and into the cloud, your physical environment is not longer a point of concern for anyone but yourself.
As for working over WiFi, you should be fine. (Assuming you have good Internet and good WiFi - WiFi has many generations and is subject to distance and construction material limitations). Remember, WiFi is a LAN technology and has nothing to do with your remote users as they will have their own WiFi in their home.
If you are just starting out, make it easy for yourself. Embrace the cloud. Avoid building on-prem infrastructure to support an inferior solution. Hope this is helpful.