You asked for a cabin filter and there is only one that I know of. It is accessed from the outside rear of the cab. The air filter for the engine is under the hood and consists of an inner and outer filter.
Do you know if your tractor is a L5240 or L5240-3?
Here's the outer for a L5240-3. Kubota: ASSY ELEMENT, OUTER, Part # TD270-93230 Kubota: ASSY ELEMENT, OUTER, Part # TD27-9323
Inner for L5240-3: Kubota: ELEMENT, INNER A, Part # TD270-93220, Kubota: ELEMENT, INNER A, Part # TD27-9322