Here are the classes, structs, unions and interfaces with brief descriptions:

CAFSKClient	Client for audio-based transmissions. Requires Arduino tone() function, and a module capable of direct mode transmission using DIO pins
CAX25Client	Client for AX25 communication
CAX25Frame	Abstraction of AX.25 frame format
CCC1101	Control class for CC1101 module
CESP8266	Control class for ESP8266 module. Implements TransportLayer methods
CHC05	Control class for HC05 module. Most methods supported by this module are implemented in ISerial interface
CHellClient	Client for Hellschreiber transmissions
CHTTPClient	Client for simple HTTP communication
CISerial	Interface class for Arduino Serial. Only calls the appropriate methods for the active UART interface
CITA2String	ITA2-encoded string
CJDY08	Control class for JDY08 module. Most methods supported by this module are implemented in ISerial interface
CModule	Implements all common low-level SPI/UART/I2C methods to control the wireless module. Every module class contains one private instance of this class
CMorseClient	Client for Morse Code communication. The public interface is the same as Arduino Serial
CMQTTClient	Client for simple MQTT communication
CnRF24	Control class for nRF24 module
CPhysicalLayer	Provides common interface for protocols that run on LoRa/FSK modules, such as RTTY or LoRaWAN. Also extracts some common module-independent methods. Using this interface class allows to use the protocols on various modules without much code duplicity. Because this class is used mainly as interface, all of its virtual members must be implemented in the module class
CRF69	Control class for RF69 module. Also serves as base class for SX1231
CRFM22	Only exists as alias for Si4432, since there seems to be no difference between RFM22 and Si4432 modules
CRFM23	Only exists as alias for Si4431, since there seems to be no difference between RFM23 and Si4431 modules
CRFM95	Derived class for RFM95 modules. Overrides some methods from SX1278 due to different parameter ranges
CRFM96	Derived class for RFM96 modules. Overrides some methods from SX1278 due to different parameter ranges
CRFM97	Derived class for RFM97 modules. Overrides some methods from RFM95 due to different parameter ranges
CRFM98	Only exists as alias for RFM96, since there seems to be no difference between RFM96 and RFM98 modules
CRTTYClient	Client for RTTY communication. The public interface is the same as Arduino Serial
CSi4430	Derived class for Si4430 modules
CSi4431	Derived class for Si4431 modules
CSi4432	Derived class for Si4432 modules
CSi443x	Base class for Si443x series. All derived classes for Si443x (e.g. Si4431 or Si4432) inherit from this base class. This class should not be instantiated directly from Arduino sketch, only from its derived classes
CSSTVClient	Client for SSTV transmissions
CSSTVMode_t	Structure to save data about supported SSTV modes
CSX1231	Control class for SX1231 module. Overrides some methods from RF69 due to different register values
CSX1261	Derived class for SX1261 modules
CSX1262	Derived class for SX1262 modules
CSX1268	Derived class for SX1268 modules
CSX126x	Base class for SX126x series. All derived classes for SX126x (e.g. SX1262 or SX1268) inherit from this base class. This class should not be instantiated directly from Arduino sketch, only from its derived classes
CSX1272	Derived class for SX1272 modules. Also used as base class for SX1273. Both modules use the same basic hardware and only differ in parameter ranges
CSX1273	Derived class for SX1273 modules. Overrides some methods from SX1272 due to different parameter ranges
CSX1276	Derived class for SX1276 modules. Overrides some methods from SX1278 due to different parameter ranges
CSX1277	Derived class for SX1277 modules. Overrides some methods from SX1278 due to different parameter ranges
CSX1278	Derived class for SX1278 modules. Also used as base class for SX1276, SX1277, SX1279, RFM95 and RFM96. All of these modules use the same basic hardware and only differ in parameter ranges (and names)
CSX1279	Derived class for SX1279 modules. Overrides some methods from SX1278 due to different parameter ranges
CSX127x	Base class for SX127x series. All derived classes for SX127x (e.g. SX1278 or SX1272) inherit from this base class. This class should not be instantiated directly from Arduino sketch, only from its derived classes
CSX1280	Derived class for SX1280 modules
CSX1281	Derived class for SX1281 modules
CSX1282	Derived class for SX1282 modules
CSX128x	Base class for SX128x series. All derived classes for SX128x (e.g. SX1280 or SX1281) inherit from this base class. This class should not be instantiated directly from Arduino sketch, only from its derived classes
Ctone_t	Structure to save data about tone
CTransportLayer	Provides common interface for protocols that run on modules with Internet connectivity, such as HTTP or MQTT. Because this class is used mainly as interface, all of its virtual members must be implemented in the module class
CXBee	Control class for XBee modules
CXBeeSerial	XBee Serial interface. This class is used for XBees in transparent mode, i.e. when two XBees act as a "wireless UART"