sharing files with colleagues

Hello, i'm starting a small business and we have apple devices, i'm having issues sharing files with employees, i will state the problems and some notes to help you help me better:

1 - i cant use Airdrop to share big/multiple files as it takes too much time to convert and send them, and you can't use the phone when you're sending the files ( very inconvenient )

2 - i cant upload files to the internet and share them as it would take a very long time to do so, ( our internet speed isn't that good)

i'm looking for a method that shares files between my devices seamlessly and without using too much internet, ( cables is good enough but please show me the steps as i'm new.to apple devices

we have:

macbook air

macbook pro

2 iphones 12 pro max

Iphone 7

Iphone 6