LoadError when setting up new pod

I followed the instructions here to set up a dev pod in my Mac: https://wiki.diasporafoundation.org/Installation/Mac_OS/High_Sierra and https://wiki.diasporafoundation.org/Installation/Backport?db=postgres&mode=development#Versions_of_this_guide

I got all the way to ./script/server, but got these errors:

I, [2018-09-14T10:56:31.528490 #64495]  INFO -- : [diaspora:web] load_external_pid_file: pid_file not found
I, [2018-09-14T10:56:31.529109 #64495]  INFO -- : [diaspora:web] switch :starting [:unmonitored => :starting] monitor by user
I, [2018-09-14T10:56:31.533450 #64495]  INFO -- : [diaspora:web] daemonizing: `bin/bundle exec unicorn -c config/unicorn.rb` with start_grace: 2.5s, env: 'RAILS_ENV=development PORT=', <64540> (in /Users/USERNAME/diaspora)
I, [2018-09-14T10:56:31.533571 #64495]  INFO -- : [diaspora:web] sleeping for :start_grace 2.5
E, [2018-09-14T10:56:34.034116 #64495] ERROR -- : [diaspora:web] process <64540> not found, it may have crashed (you should check the process logs [nil, "/Users/USERNAME/diaspora/log/eye_processes_stderr.log"])
E, [2018-09-14T10:56:34.034209 #64495] ERROR -- : [diaspora:web] process <64540> failed to start (:not_really_running)
I, [2018-09-14T10:56:34.034773 #64495]  INFO -- : [diaspora:web] switch :crashed [:starting => :down] monitor by user
I, [2018-09-14T10:56:34.035317 #64495]  INFO -- : [diaspora:web] schedule :check_crash (crashed)
I, [2018-09-14T10:56:34.035381 #64495]  INFO -- : [diaspora:web] <= monitor
I, [2018-09-14T10:56:34.035428 #64495]  INFO -- : [diaspora:web] => check_crash  (crashed)
W, [2018-09-14T10:56:34.035489 #64495]  WARN -- : [diaspora:web] check crashed: process is down
I, [2018-09-14T10:56:34.035532 #64495]  INFO -- : [diaspora:web] schedule :restore (crashed)
I, [2018-09-14T10:56:34.035569 #64495]  INFO -- : [diaspora:web] <= check_crash
I, [2018-09-14T10:56:34.035599 #64495]  INFO -- : [diaspora:web] => restore  (crashed)

When I checked eye_processes_stderr.log as the error suggested, I see these outputs:

bin/bundle:3:in `load': cannot load such file -- /Library/Ruby/Site/exe/bundle (LoadError)
	from bin/bundle:3:in `<main>'

I’m not sure what they mean and would appreciate any help!