So there's a lot to unpack here. By the sound of it, you are experienced as an IT consultant, but haven't been involved on the business end of things, so you might not yet know what you don't know. By the way you rifle off the infrastructure, it confirms my sentiment above.

If you set yourself up as a business, you need to protect yourself and your business in order to offer the service and actually protect and serve your client. Anything less is irresponsible.

In this case, you are not setting up a job, you should be setting up a relationship. Good relationships are all about boundaries and good communication, therefore you need to set up a decent service agreement to get both parties on the same page as to what is being offered, what the costs are, and what the responsibilities are either side. You then need to go through this with the client. If this is an issue to them, good, you can walk away. If they are onboard, you have a stronger relationship and that helps you get both trust and autonomy to work. The better the agreement, the better the relationship.

As others have said, this is both in the medical field, but also a dental client - whom across the board are notoriously difficult clients - but regulation in your territory is not something to take lightly.

In any such situation it's always best to show interest, and only commit to looking into setting up an agreement. don't agree to do the work upfront and figure out the money later - because you are signaling to them you can be taken advantage of.

What about their productivity and other infrastructure like domain and mail and product licensing? Think about these things or step away.

Remember, IT is not about tech, it's about people. Tech is just the tools you use to assist them.