Build failed for ttgo-lora32-v21

[FountainOfInk]

Clicking the PlatformIO: Build icon in the GUI results in the following output (Please tell me if you would prefer a pastebin!):

This seems to be an issue with PlatformIO being unable to find dependencies, but I'm not sure how to resolve it. Please tell me if I'm doing something wrong!

 *  Executing task: platformio run --environment ttgo-lora32-v21 

Processing ttgo-lora32-v21 (platform: espressif32; board: ttgo-lora32-v21; framework: arduino)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/ttgo-lora32-v21.html
PLATFORM: Espressif 32 (6.8.1) > TTGO LoRa32-OLED v2.1.6
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES: 
 - framework-arduinoespressif32 @ 3.20017.0 (2.0.17) 
 - tool-esptoolpy @ 1.40501.0 (4.5.1) 
 - toolchain-xtensa-esp32 @ 8.4.0+2021r2-patch5
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 35 compatible libraries
Scanning dependencies...
Dependency Graph
|-- ArduinoJson @ 6.21.5
|-- RingOscillatorNoiseSource @ 0.4.0+sha.5f58ce5
Building in release mode
Compiling .pio/build/ttgo-lora32-v21/src/Cryptography/CBC.cpp.o
Compiling .pio/build/ttgo-lora32-v21/src/Cryptography/Ed25519.cpp.o
In file included from src/Cryptography/CBC.cpp:23:
src/Cryptography/CBC.h:26:10: fatal error: Cipher.h: No such file or directory

****************************************************************
* Looking for Cipher.h dependency? Check our library registry!
*
* CLI  > platformio lib search "header:Cipher.h"
* Web  > https://registry.platformio.org/search?q=header:Cipher.h
*
****************************************************************

 #include <Cipher.h>
          ^~~~~~~~~~
compilation terminated.
Compiling .pio/build/ttgo-lora32-v21/src/Cryptography/Fernet.cpp.o
*** [.pio/build/ttgo-lora32-v21/src/Cryptography/CBC.cpp.o] Error 1
In file included from src/Cryptography/Ed25519.cpp:1:
src/Cryptography/Ed25519.h:5:10: fatal error: Ed25519.h: No such file or directory

*****************************************************************
* Looking for Ed25519.h dependency? Check our library registry!
*
* CLI  > platformio lib search "header:Ed25519.h"
* Web  > https://registry.platformio.org/search?q=header:Ed25519.h
*
*****************************************************************

 #include <Ed25519.h>
          ^~~~~~~~~~~
compilation terminated.
*** [.pio/build/ttgo-lora32-v21/src/Cryptography/Ed25519.cpp.o] Error 1
In file included from src/Cryptography/Fernet.h:3,
                 from src/Cryptography/Fernet.cpp:1:
src/Cryptography/Random.h:5:10: fatal error: RNG.h: No such file or directory

*************************************************************
* Looking for RNG.h dependency? Check our library registry!
*
* CLI  > platformio lib search "header:RNG.h"
* Web  > https://registry.platformio.org/search?q=header:RNG.h
*
*************************************************************

 #include <RNG.h>
          ^~~~~~~
compilation terminated.
*** [.pio/build/ttgo-lora32-v21/src/Cryptography/Fernet.cpp.o] Error 1
================================================================================ [FAILED] Took 1.61 seconds ================================================================================

Environment      Status    Duration
---------------  --------  ------------
ttgo-lora32-v21  FAILED    00:00:01.614
=========================================================================== 1 failed, 0 succeeded in 00:00:01.614 ===========================================================================

 *  The terminal process "platformio 'run', '--environment', 'ttgo-lora32-v21'" terminated with exit code: 1. 
 *  Terminal will be reused by tasks, press any key to close it.