Code written from YouTube video https://youtu.be/00gPK3rfXZA

init.lua

local username = 'ADAFRUIT_IO_USERNAME'
local aioKey   = 'ADAFRUIT_IO_KEY'
local feed     = 'ADAFRUIT_IO_MQTT_FEED_NAME'

local sda = 26
local scl = 27
local sla = 0x3c

i2c.setup(i2c.HW0, sda, scl, i2c.FAST)
local disp = u8g2.ssd1306_i2c_128x64_noname(i2c.HW0, sla)

disp:setFont(u8g2.font_6x10_tf)
disp:setFontRefHeightExtendedText()
disp:setDrawColor(1)
disp:setFontPosTop()
disp:setFontDirection(0)

disp:clearBuffer()

local messages = {}
local maxMessages = 6

local function appendMessage(msg)
    if #messages >= maxMessages then
        for i = 1, maxMessages - 1 do
            messages[i] = messages[i + 1]
        end

        messages[maxMessages] = msg
    else
        table.insert(messages, msg)
    end

    disp:clearBuffer()

    for i, m in pairs(messages) do
        disp:drawStr(0, (i - 1) * 10, m)
    end

    disp:sendBuffer()
end

appendMessage('~Initializing...')

local client = mqtt.Client('clientx', 120, username, aioKey)

client:on('connect', function() appendMessage('~Connected') end)
client:on('offline', function() appendMessage('~Disconnected') end)

client:on('message', function(_, topic, data)
    print(topic, '>', data)
    appendMessage(data)
end)

function connect()
    client:connect('io.adafruit.com', 1883, 0, function()
        client:subscribe(username .. '/f/' .. feed, 0, function()
            appendMessage('~Subscribed')
        end)
    end,
    function(_, reason)
        print('mqtt error', reason)
        appendMessage('~Error')
    end)
end

wifi.mode(wifi.STATION)

wifi.sta.config({
    ssid  = 'Renault 1.9D',
    pwd   = 'renault19',
    auto  = false
})

wifi.sta.on('got_ip', connect)

wifi.start()
wifi.sta.connect()