It boggles the mind that there are now software developers who apparently have no concept of building software for people to install on their own computer(s).
This is an option but it's too much of a hassle. You can't store the company data all on one single computer. An alternative would be to create some sort of intranet inside the company only for this data. This would also mean that we can only process the data if the computer was open.
> This would also mean that we can only process the data if the computer was open.
The whole point of keeping the data on computers a client controls is that they have control over it - if you're just going to pull it out somewhere else for fuck knows what purposes, it defeats the purpose of them storing the data.
The solution is to have software that is installed on computer(s) they control. Whether "process" you need to run should run on their computer(s), under their control.
If that is "too much of a hassle", it sounds like they'll be better served by a vendor that actually understands their concerns and requirements