Discord.Js Server Welcome

Welcome message when joining discord Server using discord.js

If you read the documentation, there's is no message parameter, only member. You will have to get the guild's channel ID first.

Try something like this:

bot.on('guildMemberAdd', member => {
    member.guild.channels.get('channelID').send("Welcome"); 
});

Discord.js V13 Welcome Message

You need GUILD_MEMBERS intent in both the code and discord developer portal.

const client = new Client({ 
    intents: [
        Intents.FLAGS.GUILDS,
        Intents.FLAGS.GUILD_MESSAGES,
        Intents.FLAGS.GUILD_MEMBERS //also enable in discord developer portal
    ] 
})

To answer the other part of your other question, the .send exists on TextChannels. TextChannel extends BaseGuildTextChannel which extends GuildChannel. It's like this because it can be a VoiceChannel!

Discord.JS: Welcome message

client.on("guildMemberAdd", (member) =>
  client.channels.cache.get("789830758331318273").send({
  //put your channel id in replace of "789830758331318273"
    embed: {
      title: "Joined",
      description: `\n <@${member.id}> joined the server. There are now \`${member.guild.memberCount}\` in the server \nWelcome <@${member.id}> :wave:`,
      color: config.color,
    },
  })
);

discord.js event handler welcome message

The issue lies within the welcome code.

In the handler code you have the following line:

client.on(event.name, (...args) => event.execute(...args, Discord, client));

This triggers the client on the name property set in the welcome code.

You currently have it set to welcome, which is not a valid event.
The bot is now listening for a welcome event, which will never happen.

First course of action is setting the name property to guildMemberAdd like this:

module.exports =  {
    name: 'guildMemberAdd',
//the rest of the code

Then you have another issue.
Within the welcome code you have client.on() again.

This will never work, unless by some incredibly lucky chance 2 people join within a millisecond of each other, but even then you'll only have 1 welcome message.

Removing the following:

client.on('guildMemberAdd', (member) => {
//code
})

will fix that issue.

Then the last thing to do is having the member value being imported correctly.
We do this by changing the following line:

execute(Discord, client) {

to:

execute(member, Discord, client) {
//code

The resulting code will look like this:

module.exports =  {
    name: 'guildMemberAdd',
    once: false,
    execute(member, Discord, client) {

    const welcomechannelId = '753484351882133507' //Channel You Want to Send The Welcome Message
    const targetChannelId = `846341557992292362` //Channel For Rules

            let welcomeRole = member.guild.roles.cache.find(role => role.name === 'Umay');
            member.roles.add(welcomeRole);

            const channel = member.guild.channels.cache.get(welcomechannelId)

            const WelcomeEmbed = new Discord.MessageEmbed()
            .setTitle(`Welcome To ${member.guild.name}`)
            .setThumbnail(member.user.displayAvatarURL({dynamic: true, size: 512}))
            .setDescription(`Hello <@${member.user.id}>, Welcome to **${member.guild.name}**. Thanks For Joining Our Server.
Please Read ${member.guild.channels.cache.get(targetChannelId).toString()}, and assign yourself some roles at <#846341532520153088>. You can chat in <#753484351882133507> and talk with other people.`)
         // You Can Add More Fields If You Want
            .setFooter(`Welcome ${member.user.username}#${member.user.discriminator}`,member.user.displayAvatarURL({dynamic: true, size: 512}))
            .setColor('RANDOM')
        member.guild.channels.cache.get(welcomechannelId).send(WelcomeEmbed)

    }
}

Happy coding!

Welcome message in a specific channel when a user joins the server. (guildMemberAdd, discord.js)

This is because you are not requesting the GUILD_MEMBERS intent.

const Discord = require("discord.js");
const client = new Discord.Client({ intents: ["GUILDS", "GUILD_MESSAGES", "GUILD_MEMBERS"] });
const { MessageEmbed } = require('discord.js');

client.on("ready", () => {
    console.log("Cloud Shield has been activated.")
});

client.on("guildMemberAdd", async (member) => {
    console.log(member);
});

client.login(process.env.token)