You seem to have some misconceptions about how Internet can be provided.
Internet services can be delivered by an ISP over a wired connection (DSL on a phone line, or cable as used by TV companies), optical fibre, satellite or a cellular network. This is just a basic connection. It is not specifically Ethernet, USB or WiFi, which are all short range interfaces that are good only for a a few metres. Ethernet is specified for use up to 100 metres (without a repeater of some sort). WiFi range varies, but even outdoors the distance will rarely reach 100 metres. USB is much shorter.
There are such things a Microwave Links that can span distances of a few miles. These are NOT WiFi links although they use a wireless technology. They require an ISP connection at one location and a line-of-sight path to the second location to carry the Internet connection to that second location.
You say "I am not able to get a Wi-Fi service connection on my phone". The phone does get a WiFi service connection. If it is a cell phone it gets a cellular network connection that can carry voice and data services. If you are within range of a suitable cell tower and you have the appropriate features in the phone and your contract with the cell company, then you can get Internet on the phone. You have to enable the WiFi hotspot in the phone if you want to extend that Internet connection using WiFi a few metres to other devices. If it is a land-line based phone, then it will depend upon whether the phone company also offers an Internet service over their lines. With DSL, this may not be possible over very long lines.
In each case you need a modem. A modem converts between whatever signal type is carried over the connection to the ISP and a digital form that can be used by other devices. A router typically provides the mechanism to allow multiple devices to be connected to a single path to your ISP or other network. A smart cell phone has a built in modem function that allows it to receive an Internet connection over the cell network and, when its hotspot is enabled, a router function that provides local WiFi.
WiFi does not come from an ISP, it is a locally generated interface produced by a wireless router, a wireless access point or a hotspot of some sort and will normally have to be within 100 metres (outdoors) and may be a little as 5 metres (indoors). WiFi does not mean Internet access. You can set up your own WiFi network simply by installing a wireless router. This will allow you to network various local devices to work together, but on its own it will not mean you have Internet access.
From what you have said in your question, the DIY part of what you are doing will relate to the work you are doing to convert the cabin. If it is as remote as your question implies, getting Internet access is likely to require serious professional help.