Any audio interface that supports ASIO or WASAPI (Windows) and Core Audio (MacOS) can be used in the Soundtrap studio. For Chromebooks, we strongly suggest reaching out first to your device manufacturer, as its compatibility may vary depending on your Chromebook's make and model.
There's a wide range of audio interfaces on the market from small and easy-to-use affordable ones to very expensive ones with a lot of technical features. Even the affordable ones can result in very good sound quality. A 2-channel plug-and-play (PnP) USB audio interface should work across most (if not all) devices/operating systems.
There are also USB mics on the market. With these kinds of microphones, you don’t need an audio interface to connect to your computer. You just plug in the USB cable from the mic and record.
Always check with the manufacturer if they support the audio interface on the operating system (OS) of the device you’ll be using.
Audio interfaces that don’t connect via USB may require additional gear/tools to work in Soundtrap (eg. DIN cables).