Why can't I install boards on Arduino Create

I am trying to upload code from Arduino onto an Adafruit Trinket MO. Even though I have downloaded the proper boards on the downloaded version it still doesn't work(different post). I thought if I could go onto Arduino create online and download the Trinket MO board used with the Arduino plugin, that might work. It appears that the online version only has Adafruit Circuit Express and Adafruit Feather support. Why is there no Trinket MO board on the online version even though I am paying monthly for the online Adafruit support. The downloaded version has support for these boards (allegedly, mine has yet to work) and it is free!

I suspect one reason why you can't install arbitrary 3rd party boards on Arduino Web Editor is security. When you install a 3rd party hardware package, you also install the toolchain. When you compile, you are running the executable files from that board's toolchain. That opens up the doors for a lot of potential mischief by bad people.

Another factor is storage space. Your Create Maker plan gives you 200 MB of disk space. That's plenty for sketches and libraries, but you would run out of that 200 MB very quickly if you started installing toolchains.

gsutherland2:
It appears that the online version only has Adafruit Circuit Express and Adafruit Feather support.

Those boards are part of the hardware packages that were already installed (Arduino AVR Boards and ESP8266 Core for Arduino). Arduino didn't have to do anything special to install them.

gsutherland2:
I am paying monthly for the online Adafruit support.

Would you mind posting a link to where it says your Create Maker plan comes with Adafruit support? I did a little bit of looking around in the Arduino Create documentation and couldn't find anything about that. If I could read the exact wording, it would help me to answer your question.

The PAID plan does support a selection of the Adafruit boards.
Current list below and can also be found in the HELP section of CREATE itself.

Arduino/Genuino 101
Adafruit Circuit Playground
Adafruit Circuit Playground Express
Adafruit Feather HUZZAH ESP8266
Analog ADI (Native USB Port)
Analog ADI (via Atmel-ICE)
Arduino Due (Native USB Port)
Arduino Due (Programming Port)
Arduino Duemilanove
Arduino Esplora
Arduino Ethernet
Arduino Industrial 101
Arduino Leonardo
Arduino Leonardo ETH
Arduino M0
Arduino M0 Pro (Native USB Port)
Arduino M0 Pro (Programming Port)
Arduino Mega ADK
Arduino Mega or Mega 2560
Arduino Micro
Arduino Mini
Arduino MKR FOX 1200
Arduino MKR GSM 1400
Arduino MKR NB 1500
Arduino MKR Vidor 4000
Arduino MKR WAN 1300
Arduino MKR WAN 1310
Arduino MKR WiFi 1010
Arduino MKR1000
Arduino MKRZERO
Arduino Nano
Arduino Nano 33 BLE
Arduino NANO 33 IoT
Arduino Nano Every
Arduino Primo
Arduino Primo Core
Arduino Pro or Pro Mini
Arduino Robot Control
Arduino Robot Motor
Arduino Tian
Arduino Uno
Arduino Uno WiFi
Arduino Uno WiFi Rev2
Arduino Yún
Arduino Yún Mini
Arduino Zero (Native USB Port)
Arduino Zero (Programming Port)
ARM Linux Generic SBC
EMoRo 2560
ESP8266 4D Systems gen4 IoD Range
ESP8266 Amperka WiFi Slot
ESP8266 Arduino
ESP8266 Digistump Oak
ESP8266 LOLIN(WEMOS) D1 mini Lite
ESP8266 LOLIN(WEMOS) D1 mini Pro
ESP8266 LOLIN(WEMOS) D1 R2 & mini
ESP8266 Phoenix 1.0
ESP8266 Phoenix 2.0
ESP8266 Seeed Wio Link
ESP8266 WeMos D1 R1
ESP8266 WiFiduino
ESP8266 WifInfo
ESP8266 XinaBox CW01
ESPDuino (ESP-13 Module)
ESPectro Core
ESPino (ESP-12 Module)
ESPresso Lite 1.0
ESPresso Lite 2.0
Generic ESP8266 Module
Generic ESP8285 Module
Industruino D21G
Intel x86_64 Boards / IoT Gateways
LilyPad Arduino
LilyPad Arduino USB
Linino One
littleBits w6 Arduino Module (Leonardo)
NodeMCU 0.9 (ESP-12 Module)
NodeMCU 1.0 (ESP-12E Module)
Olimex MOD-WIFI-ESP8266(-DEV)
SmartEverything Dragonfly (Native USB Port)
SmartEverything Dragonfly (via Atmel-ICE)
SmartEverything Fox (Native USB Port)
SmartEverything Fox (via Atmel-ICE)
SmartEverything Fox3 (Native USB Port)
SmartEverything Fox3 (via Atmel-ICE)
SmartEverything Lion (Native USB Port)
SmartEverything Lion (via Atmel-ICE)
SmartTutto (Native USB Port)
SmartTutto (via Atmel-ICE)
SparkFun ESP8266 Thing
SparkFun ESP8266 Thing Dev
SweetPea ESP-210
ThaiEasyElec's ESPino
UP² Board
Arduino Create Plugin - The

The only way to use CREATE and be able to add boards is to install the server version IIRC.
Clearly that involves a lot more than the regular desktop IDE and is only useful for larger use scenarios.

Another option in some respects is to use an RDP approach to the desktop IDE.

Bob.