So there are a couple things wrong here. First you have 2 “clients” defined

// first client
const bot = new Discord.Client({intents: ["GUILDS", "GUILD_MESSAGES", "GUILD_MEMBERS"]})
// second client 
const client = new Discord.Client({
    intents: [
      Discord.Intents.FLAGS.GUILDS,
      Discord.Intents.FLAGS.GUILD_MEMBERS,
    ],
  });

Then your code reads as follow

bot.on(‘guildMemberAdd’, async member => {
// above line states that the first client will do something when a member joins

client.channels.cache.get('ChannelHere')
//above line states that the second client will retrieve the channel
…

channel.send(`please welcome ${member} to the server!`, embed)
//above line has the first client doing something (sending a message) however the first client didn’t retrieve the channel so channel.anything won’t work.
client.channels.cache.get("775086826154229840").send(`please welcome ${member} to the server!`, embed)
//this line would technically work except client isn’t logged in, bot is and you needed the .cache part
msg.channel.send(`please welcome ${member} to the server!`, embed)
// msg is not defined probably just need to delete msg
});
}

Try this and it should work

const Discord = require('discord.js')

// if using discord v12 pick only one bot
const bot = new Discord.Client({intents: ["GUILDS", "GUILD_MESSAGES", "GUILD_MEMBERS"]})

// if using discord v13 pick only one bot
const bot = new Discord.Client({
intents: [Intents.FLAGS.GUILDS, Intents.FLAGS.GUILD_MEMBERS, Intents.FLAGS.GUILD_MESSAGES]
})

const config = require('./botconfig.json')
const prefix = '...';
const welcome = require("./welcome");
const Welcome = require("discord-welcome");

bot.on('ready', async () => {
    console.log(`${bot.user.username} is online and in ${bot.guilds.cache.size} server!`)
}) 

// START OF WELCOME BOT
bot.on('guildMemberAdd', async member => {
    const channel = bot.channels.cache.get('ChannelHere')
    let embed = new Discord.MessageEmbed()
    .setTitle('TESTING EMBED')
    .setDescription('TITLE LAUNCHED...')
    .setColor("#ffd8e3")
   
    // if using discord v12
    channel.send(`please welcome ${member} to the server!`, embed)
    
    // if using discord v13
    channel.send({
        content: `please welcome ${member} to the server!`,
        embeds: [embed]
    })
});
// END OF WELCOME BOT



bot.login(config.token)