I use ConnectBot (https://f-droid.org/en/packages/org.connectbot/).

It will require you setup ssh access, and as I have no Mac I can't offer any suggestions on how to do that with a Mac.

I use the "Windows App" on iPad to remote desktop into my Windows computer. Works fine despite my computer being on the wrong side of an ADSL connection, it's great for my work computer which has a much faster connection.

For extended use a $5 plastic clip from AMZN and any bluetooth mouse and keyboard works great, as good as a laptop and sleeker too if I am working on a desk. I can do simple things with just touch while riding the bus, sitting at the beach, etc.