The ISA One can be connected to an audio interface in two ways - using analogue cables between the ouputs of the ISA One and the audio interface, and digitally (providing the optional analogue to digital converter card is installed and the audio interface has a digital input).
The simplest way of connecting the ISA One to the audio interface is to use the Main XLR Output. This will output the input source that is selected on what is selected on the front panel (mic, line or instrument). If you wish to record a mic or line input at the same time as an instrument (guitar or bass) through the ISA One the DI XLR Output can also be used. This will require you to have 2 line inputs available on your audio interface.
As both of these analogue outputs are 3-pin XLR connections, you will need a female XLR connector on one end of the cable and either male XLR or male TRS Jack connector on the other end, depending on the type of line input connection your audio interface has.
ISA One can be used as a high-quality two-channel ADC to convert the analogue signals to various digital formats (AES, S/PDIF and ADAT), by installing the optional analogue to digital converter card (ADC). This will allow you to connect the ISA One to the digital inputs on an audio interface.
When connecting in this way, it is advisable for the ISA One to be the digital clock master and the audio interface to digitally sync to the ISA One - presuming there are no other devices in the signal chain. Please see this article for information regarding digitally syncing your ISA One to an audio interface.
Note: More in-depth information regarding the ISA One can be found in the User Guide which can be downloaded from here.