Successfully setting up a WiFi adapter on Raspberry Pi depends on the right choice of the appropriate wifi adapter. The selection of WiFi adapters for the USB is huge. But not all adapters are equally well suited.

The device can be easily connected or with considerable effort. The reason is the different chipsets and the compatibility of drivers and operating system.

If you already have a wireless adapter, you can of course try it, but you should be prepared for problems. If you do not have one, you can get one. Compatibility lists are helpful or the hint in the product description shows that the WiFi adapter works with Raspberry Pi. For example, tested on Amazon and eBay Wi-Fi adapters are offered.