About installation

[ByEzel93]

Hello teacher, first of all, thank you very much for making our backgammon. Even though yarn is installed on my server, I cannot start the project. I'm getting an error like the following. Can you help me with the installation?

system_check | Starting with pid of 3682495
web | Starting with pid of 3682496
assets Starting with pid of 3682497
assets sh: yarn: command not found
assets Done
system_check | There is a problem with your system setup:
system_check | Yarn is not installed
system_check | See https://yarnpkg.com/lang/en/docs/install/ for install instructions.
system_check |
system_check | Done
web | In tasks.cr:12:1
web |
web | 12 | require "./src/app"
web | ^
web | Error: while requiring "./src/app"
web |
web |
web | In src/app.cr:1:1
web |
web | 1 | require "./shards"
web | ^
web | Error: while requiring "./shards"
web |
web |
web | In src/shards.cr:2:1
web |
web | 2 | require "dotenv"
web | ^
web | Error: can't find file 'dotenv'
web |
web | If you're trying to require a shard:
web | - Did you remember to run `shards install`?
web | - Did you make sure you're running the compiler in the same directory as your shard.yml?
web | Done